I recently bought a new one and I dismissed the laminate trimmer as not up to the job.

Most laminate trimmers do not have the fine adjustments and capacity to fit accurate guides like larger 'routers'. Laminate trimmers also generally do not have the ability to plunge into the work from above and probably don't have the grunt to use larger bits.

If you are mainly using it for board repairs you could go a 1/4 inch or 1/2 inch. The 1/4 inch will be lighter and easier to control. A 1/2 inch will (as DAR says) be able to take longer bits (good if you want to router out a finbox- using something like this one with 63mm cutter depth https://www.trend-uk.com/en/UK/product/3_85X1_2TC/4/28/two_flute_cutter_127mm_diameter.html) and also have more grunt to do this sort of work.

Clarence

^^^ agreed.
You don't need to run an inch wide cutter to fit fin boxes - you can make more than one pass.
You don't need a 40mm deep cutter, again you can make more than one pass.
1/2" collet is overkill

I use a mega powerful trade quality 1/4" shank router - only as I got it free.
It has plenty of grunt and easily cuts through anything on a board - but the trouble is
(1) the weight of it compresses foam so it cuts "over deep" just a little if used on foam. And this is just with a good 1/4" collet router, a heavier 1/2" would be worse
That's why surf shapers use a little trim router to inlet for fin box installs.

(2) the limiting factor is often the bit. I find cheap bits overheat and blunt in composites. So the one you use often needs to be quality. $10 ones from eBay or Bunnings' cheapest at about $15 work a couple of times then they're stuffed. Well, still good for foam but not glass and wood sandwich etc.

I really think you kinda need both. Unless you are sure all you will ever do is tear out sandwich for repairs (powerful 1/4" router with a $40 bit) , or only ever do FCS box installs and foot strap inserts (trim router with any old bit).

I use the big router (1/4" collet but big motor) for cutting thru composite skins and removing a whole mast track or something.
I use my Dremel with an extra long 1/8" mill bit for foam only, to freehand a surf box install or similar.

If I had to pick only one, I'd go a quality trim router as they are light and the Hp matters less than a good quality bit and revs.

Oh - and get one with plenty of gap from motor to base plate so you can see what you are doing and also hold a vacuum cleaner hose in there whilst cutting. Seems dust is not as annoying as fibres hitting your face and throat at 300kph.