I think that it's difficult to find a place where you would have a bad feed here, although some places are definitely better than others. There is such a huge range of cuisines and, in the main, many restaurants supplying each of them, that the choices are endless. I have eaten at only a small percentage of the restaurants on this island and these are my favourites:

Thai Food:

Tho's Restaurant at Thalang located just south of the traffic lights near the Honda dealer - Every dish is just superb.

Sabai Sabai Restaurant in Soi C&N in Patong. Walk down the Soi past the many massage shops and it's on the right. Superb Thai food at very reasonable prices and the western dishes are good as well. 

Da's Restaurant  next to the Two Black Sheep on Rat-U-Thit Road in Patong, has a well deserved reputation and is a very popular eatery;

  Kata Mamas at the South end of Kata Yai Beach has very good food and the location is very hard to beat. The Rasta Bar next door is a great place for a drink.

 Champion Restaurant at Mae Ubon Market on Nanai Road in Patong (second in from the road) serves delicious food. All of the dishes are superb. Gravy noodles with chicken, bar-b-qued chicken or pork are especially recommended.

 Pan Yaah Restaurant at Kalim Bay (around Kalim Bay opposite the construction on the hill) is more up market and has spectacular views across Patong Bay. For the romantics.

  Cherng Long Thai B B Q near Central Festival is a great place for a night out. 129 Baht for a cook yourself barbeque buffet. As much as you can eat. An event to be experienced.

 Lotus Restaurant at Bang Thao Beach behind Laguna is located right on the beach. has a great menu and delicious food. One of many excellent restaurants in the area.

 Godzilla's in front of Super Cheap in Phuket Town has great Thai food and you really won't believe the prices. Hard to beat for both quality and price.

Pak Naam in Phuket Town has wonderful food at reasonable prices. Seafood is their specialty although all of the food there is superb. The curried crab meat is the best that I have had. Often packed with diners, it's advisable to arrive early or book ahead to ensure a good table.

.........................................................................

Western Food:

Molly Malone's on the beach road and Scruffy Murphy's in Bangla Road, Patong. These Irish theme bars serve big portions of excellent food. The Guiness and Beef Pie is superb.

The Bar B Q Hut in Patong is the place to go for Mexican food and a good breakfast. You can find it on the southern end of Rat-U-Thit Road. If you're heading south it's on your right opposite the Mercure. Excellent frozen margaritas here.

The Chicago Steakhouse on the beach road in Patong is a top class establishment. The steaks are superb, the salad bar is excellent, and the service is second to none. Very impressive in all areas including location. Highly recommended.

 ...................................................................

Indian Restaurants:

I don't particularly frequent Indian Restaurants although I won't say no to some Nan bread and Hummus. While I haven't had Indian food for quite a while, I have eaten at the Dubai Restaurant on quite a few occasions and I'll go back there for my next Indian feed. They have two locations in Patong  that I recommend. One in the vicinity of Christin Massage on Rat-U-Thit Road  and one on the northern end of beach road, near the soccer fields.

.....................................................................

Japanese Restaurants:

  I recently ate at the Samurai Restaurant on the recommendation of a friend, formerly a long time resident of Japan. He gives the place top marks and I certainly enjoyed my meal. You can find it on the left side of the Royal Paradise in-road in Patong. While I haven't eaten at either the Sumo Restaurant or the Zen Restaurant, both in Patong,  they seem to be quite popular. I have eaten at the Oishi buffet in the Index Living Mall near Big C a couple of times, and would certainly recommend the food there.