Not worth the hassle. As I said, we differ in taste. Some have a working pallet, and some don´t. Anyway, I will give you a few choices:
Koh Chang: Babylon Koh Chang, Koh Chang Seafood, Sea Breeze, Siam Kitchen
Koh Samui: Saffron Banyan Tree, Phensiri Thai, The Island View, Sala Thai
Koh Tao: Bansong Kitchen, Simple Life
Koh Samed: Summerday
As I say, up to you.