Budget
The Boat Cafe
On airport rd opposite the 7-11 has no sign in english but is easily recognizable from the old long tail boat outside which they use to serve up thom yum and other thai soups at lunchtime. dishes cost 20-35 baht, and the best recommendation is the large number of locals coming in for an evening meal.
Pang's Kitchen
On airport rd just before onestop dive centre and next to hertz car rental. small traditional thai restaurant with really good food and prices. the 'jim jum' very traditional thai dish that few restaurants sell due to the need for charcoal cookers was awesome and really good fun to eat with friends. the spring rolls were the best i've tasted in ao nang.
For cheap eats, there are a few street carts scattered about, although most serve backpacker fare like banana pancakes 15 baht a pop. The fried chicken lady in front of the Tipa Resort does a pretty mean som tam papaya salad at 40 baht though, and also look out for the yellow-signed noodle stalls with a "4" in a bowl as their logo, which dish out a garlicky but tasty bamii muu daeng roast pork noodles for 25 baht.
The Pad Thai served in in a stall named "Kai Tieun Restaurant" is good and cheap. The noodle itself is not spicy and you need to add the condiments available on the table to make it spicy.
The stall in front of the Adidas Store serves rice-type lunches at 20-30 baht a box. The "Kao Nam" similar to Nasi Briyani in Malaysia is superb. Be careful before ordering "Keng Mu" Minced spicy chicken meat with rice though, be prepared to gulp in lots of water to counter the spiciness.
Generally the places along the beach are more expensive and the ones up the hill tend to be cheaper and better value.
Midrange
Bernies Place
Offers a daily all you can eat bbq for 250 baht or 150 baht for vegetarians. the food is great and well-prepared, and there is a 2-for-1 happy hour from 16:00-18:00 and again from 22:00-23:00. located on the southern end of the beach road between the irish rover and the ocean mart.