I started 18 months ago on a brand I trusted from wind and kitesurfing. Two winged locally back then, now 30+ newbies' who buy what other locals tell them, affordability, magazine and internet-user reviews/experiences. No one buys because some hot shot surfed a giant wave on a photoshoot.
Once you are into a foil brand, maybe board brand and less so wing brand it is expensive to gamble on a change. I changed board and foil due to reliability and poor warranty support, which was costly.
So wonder why others chose what they did and if they changed, why?

I found a dealer recommended by a friend and relied heavily on the dealer's advice which worked out very well for me. This sport is incredibly expensive so I try and rely on the experts for advice. Find a good dealer with a good name.

Interesting question, I'd say most of the guys and gals in my area buy what they believe will work for their skill level and not be too much of a challenge. I only buy used and coming from a surfing background got my board because it looked like a surf board and made me feel comfortable. I chose the foil on price, availability and being rock solid, wings I chose by size and handles that I can grab hold of - right now I just want a longer mast, then after that tighter better performing wings

I've bought most of my kit with price as most important factor. I've had some not great wings, but overall the kits way better than me.
if buying again would get Axis from the start and swap bits as improvements happen, I have spent money changing from AK to Axis

I like to listen to the designers talk about what they are aiming for their gear to achieve. Scott McKercher, Alex Agera, Dave Kalama and Armie all have great philosophies and understanding of what they want their gear to achieve in my opinion.

I am lucky; started with Fanatic boards and foils and with Duotone wings. I think this combo has given me the best opportunity to learn and progress with the biggest 'fun' factor. I live by the saying, "I'm too poor to buy cheap", so try to buy only quality gear, ONCE. Upgrading is easy as I add smaller, higher performance foil sets as they just fit on. I have tried several different brands of board, foil and wing but what I have appears the best for what I am hoping to achieve.

We started early in Winging and wifey went and had lessons from 3 places that also sold gear. My partner was already kitefoiling but wanted to change to Winging from the first time she saw videos on the internet. (couldn't buy wings in Australia at this time) This was a good way to test gear. She opted for Naish due to the ease of removing the foil from the board. (Abracadabrah). We both got the same brand so we could interchange. 12 or so months later and more kit available she decided to move to all carbon and went to Armstrong. Armstrong now seem to have some quality issues with fitting of masts / fuses and bashing the mast with a hammer doesn't seem like a good solution for a premium product. She is not thinking about moving away from Armstrong.

For wings we went with Ozone, it seemed will made and seemed to work, there was only 4m available and (at the time( it was suggested that that was they only size you needed).

Board
She started on a Naish Hover and then moved to a Hover 75, never really got comfortable on it and got to try a Armstrong 75 FG, immediate winner and still loving it. However is thinking about a lower volume, flatter bottomed board with sharper rails for easier take offs with high aspect foils so probably a different brand and will keep the Armstrong as her light wind board.

Me
I stayed with my Naish kit, then when I started to look at other (MA wings) Naish didn't have many options at the time. Everything I read and was told, suggested that at my body weight a carbon mast would flex too much. I shifted to Axis as they had a lot of options, stiff masts and reasonable pricing, there was also 2nd hand options available. Happy with my choice, contemplating a HM carbon mast.

I started on a 120l Hover and moved to a 105 JP X wing board about 15 months ago. At the time the xwing seemed a good option as I was using HA foils and wanted the release. I am going to stick with the JP for now. I have the 120 still which I am using to learn on (easier to get back onto) and down winding (SUP) with a foil drive.

Wings

After the Ozone we moved to Naish wings (s25) and bought sizes around 4, 5.2, 6 then added a 3.5. At the time the Ozones only had limited sizes and nothing smaller, the Ozones also went with bigger leading edges. The Naishes were lighter and seemed to float better. My wife then moved her primary use sails to Duotone Units after some testing. She preferred the stiffer feel, stiffer handles and the wingspan was slightly less for the same size. We also noticed at the time that the ozones were almost a metre larger in area for the same labelled size. I didn't like the units so I stuck with the Naishes The newer units came out and she found these much easier to use, so we consolidated to the units. I also bought a 7m echo for light conditions so I could get out on the same wind strength as my wife.

Recently we decided to change to North Modes, nice and stiff and reasonably light, however with an apparent manufacturing issue and delivery delays and Cloud bringing out the new models we might end up with a mix of brands again.

The main driver for us has been improvement in equipment and better options for the type of winging we do. I think the incremental changes are becoming smaller which will slow the rate of equipment change over.

I think going from starting to choosing different disciplines along with different conditions drive equipment choices. I think as the sport evolves some of new designs haven't quite hit the mark, however who would have designed a winged hull for a yacht??!!! I also think that the race to the smallest has had people choose inappropriate equipment. I hope we don't go the way of wind surfing when boards were particularly narrow and all sinkers, not a good choice for weekend warriors.

I think the challenge for manufacturers will be to provide an easy upgrade path so complete kit replacements aren't required, as this gets you evaluating other brands. We also look after our kit and haven't had to change / upgrade / replace anything due to damage.

My foil journey started about 5 years ago. Bought a Naish windfoil board and foil. It was great at the time.
Upgraded the foil after a year and the second gen stuff wasn't fully compatible with the first gen stuff. Bit disappointing.
Third gen stuff also not fully compatible. Decided to move to Axis for foils when I took up winging 3 years ago based on feedback from locals who were using it. At the time, the mast to fuse joint for the Axis creamed the Naish gear for stiffness. Love the Axis gear for its build quality and the massive range of combinations. Suspect Naish have caught up now.
3 years ago, started with a Duotone Echo as I like the boom concept. Tried a Naish soft handled matador and it was terrible in terms of control compared to the boom. That said, there are plenty of much better foilers out there who make soft handles work well. I'm not a fan as my skill level probably isn't there? I notice now that most major wing brands seem to be giving a boom/handle option. I've move to the Units and Slicks now.
Duotone have experience with good quality gear from Windsurfing circles, so I've stuck with them as my experience with their wings has been very positive. I've used Smik 4m and 5m wings (about 18 months ago) and have loved the feel (slightly better than the Slicks and Units at the time). The semi rigid handles were almost as good as a proper handle. No window, which for me isn't a dealbreaker, but a big preference to have one. Where I wing is pretty crowded and even with a window I've had a few unexpected close calls.
If I was to make the journey into wingfoiling now, I reckon it would be easier in many ways as the playing field has levelled out between a lot of the brands in terms of design and build quality.

I started with an Ensis Wing 5,2 because that's what friends and family gave me as a birthday present.
Bought a Gong Foil X-Over XXL online as they are cheap.
The Station where I borrowed a Board twice didn't want to sell me any of their RRD Boards, so when I came home from my holiday I found the foil on my doorstep and went to the nearest brick and mortar shop to geht an AK Phazer 90 Liter as somebody Had said they were good and because I reckoned local support could come in handy.
Haven't regretted any of the choices:
After a year the AK died and was replaced within two days.
The Ensis Wing is still in use and Scores 4,0 and 2,8 have been added. They are powerful and you can get them below recommended retail price in some online shops.
Gong's prices have allowed me to add smaller, faster bits and pieces so I can afford doing the sport and share it with my family.
Looking for a bigger board for my honey, I happened to be offered a Naish Compact LE 115 which was almost new, cheap and the widest and shortest board in its class. Plus, it looks cool. Hasn't been tested much but seems to tick the boxes: stable shlogger, but not much swing weight once on the foil.

I really like my Gong Veloce XL. So when it was time for a smaller foil I tried the Veloce H-L, big mistake. Perhaps a good foil for long period swell but really not great in the messy chop we have. The Ypra-s might have been a better choice (and is the choice of their pro rider although it's marked for slalom).

I personally think HA foils make sense for my light wind gear but a user friendly MA is more my speed when things get crazy. Unfortunately Gong doesn't really offer that in a modern design.

Also their build quality on the new stuff is questionable.

When a complete Phantasm PTM926 came up for sale locally for a great price I took the opportunity to grab it and it's excellent. Just needs a looser tail.

I started winging last May. I had experience in windsurf (beginner-intermediate) and kitesurfing (intermediate), which was of some benefit but not huge.
I loved the look of winging from the moment I first saw it and when they broke into my car two years ago and stole all my kiting gear I decided it was time to try something new.
I was looking online for a good deal and when Gong was selling last years models at a discount I grabbed a chance and got myself a whole setup - 130L hardboard, a single 6m wing and a beginner/intermediate foil (50yrs young and 86kg). Since then I changed two boards, firstly used JP 95L X-winger and then slightly used F One rocket wing V3 88L. I added also a smaller 4m wing and upgraded foil wings to MA 1200cm2 and HA 42cm stab.
Anyway, I have always been a fan of direct sales model in general. Getting more bang for the buck if I can, why not. I knew Gong from my kiting days and did not have any serious complaints. There is a very large online winging community of mostly happy Gong customers. I have also been quite happy with their gear and if there was ever any problem they quickly sent me a replacement without too much haggle.
Going back to direct sales model: in mountain biking there are a few companies that do fantastic bikes for half of the price of usual brands. In many years of mountainbiking I have changed many big brand bikes and for the last few years I have been on direct sales YT brand bike, which is fantastic. In any case my skill level is the problem here not the bike.
So here comes my point: Winging is a new sport and surely there is a lot of progress going on with regard to gear every new model year. The thing for me personally is that I can see more skilled guys doing amazing stuff on last years gear of any brand. So if the gear was good for them it's surely good enough for my skill level. Yes, there always is gear that is newer, better, faster, but the question is if any of this is going to make a real significance for my progress. So far I have tried also some newer gear from cabrinha, epic, armstrong and f one. While there were some differences compared to some of the Gong stuff I have none of them were game changers for me.
To add another comparison (maybe its relevant or not): I have been snowboarding for around 30yrs, expert level, been snowboard instructor in my younger days. Nowdays I am mainly about powder, carving and bombing down the pists, no freestyle stuff. For almost 15yrs I had the same Sims board (high end at its time) and I replaced it last year for a swanky new one just because I felt it was time for a change. And there was no epic revelation. The new one is good, but nothing spectacular compared to the old one.

Got some F-One prototypes in my hands back when I did some windfoiling gear development for them, never switched. Its brand loyalty, price, and service level for me which made me stay. I have contemplated getting something else and asked around, but no other brand is gonna give me a reliable enough warranty. I'm a big guy pushing the gear to the limit jumping, freestyling and crashing hard as I have for years. Any brand I spoke with basically excluded what I call regular use from their warranty.