Was on Samui in April last year.
Stayed at Banyan Tree, great villas, great service, food was ok.
Had a breakfast at FS, the view is even better than the view at Banyan Tree, the facilities I could see where great, according to their website their villas seems a bit smaller, especially the pools. Breakfast at FS was much much better than in Banyan Tree.
Also tryed Napasai and found everything really bad. Although the price is much lower than at BT and FS the value for money is much worse. Villa was ok, Food was bad, Service was bad, Pool Facilites were bad and the way into the ocean is full of big stones, which made it painful to enter the water.