Food capital of asia. Bangkok is great at night time but what do you do during the days? It seems amazing at night but dreary during the days. If I had a large budget I could live on Samui but I would fly to Bangkok and other cities every month.
I know 7 quality restaurants in Chiang Mai plus they have a German buffet and that's only a fraction of the ones that would exist. Be lucky to find 2 on Koh Pha Ngan. Samui would be better, more gyms, more restaurants.
Chiang Mai has 60 baht gyms, 150 baht on Koh Pha Ngan. Chiang Mai has lots of restaurants. Islands sound good but you can see it all in 3 months or less and the food just won't match a large city.