You're asking this in the kite forum not the ding forum, so I would expect answers skewed that way.
Based on my observations:
I don't see any need to windsurf unless you already have the gear and the skills and the trailer needed to lug the gear around, and like going really really fast in a dead straight line until you reach some land where you can stop and change direction. Ding is clearly a huge evolution from that.
Ding is the king at the moment. Like SUP was 10 years ago it's super accessible for the whole family and massively trendy. However despite being easier to learn it's not as good as kite foil in almost every situation. The gear is big and heavy in comparison, the fat leading edges look like primitive 1st gen kites. .
Kite is the best wind foil. Pocket boards are superb, having no swing weight allows you to carve around in a way that massive floaty ding boards never will. Feels like flying looking down, just water in front. Having your power 25m above and being able to loop allows you to make the most of better wind than surface wind, and generate far bigger power spikes. Not having your face blocked by a huge sail is so much better, I couldn't handle doing my sport looking at a dacron wall. Tiny light gear compared to two trips to get your ding from car to beach. No leashes compared to 2 leashes to tangle when you stack.
If you live somewhere with consistent stronger wind, large running swell, and a tricky launch spot, and chase pure depowered downwind wave riding, ding beats kite for sure. In any other situation, if you have the skill, kite.