It depends on where you are staying, here are some great options:
On Property:
QS:
White Water Snacks (If you are staying at the Grand Californian, order the Nachos pool side, you will get a much larger portion for the same price, otherwise do not order the Nacos, but any other item on the menu or the off the menu Chili Cheese Fries)
Plaza Inn Chicken Dinner
Pastas at Boardwalk or the Greek Food from the window
TS:
Buffets:
PCH Grill
Plaza Inn Character Breakfast (Also the best bang for your buck on number of characters at one meal)
Non Buffets:
The Lounge next to PCH Grill (Offers some of what PCH grill used to offer and is relatively cheap, not sure if this should classify as a QS or a TS though)
Rainforest Cafe (Only if you are a Landry's member and it is near the member's birthday)
Any of the Patina Group Restaurants (If you have signed up for their birthday club on their website for free, you get $25 off a meal on your birthday, cannot be combined with other offers and you must present an I.D. for guests over 18 with the coupon)
Offsite:
Pizza place at the hotel across from the main entrance (Sorry can't remember the name right now), it is similar to Pieology and such where it is one price for as many toppings as you want, but they are substantially better and offer discounts for passholders, etc.
IHOP near Katella (Do NOT confuse this with the IHOP right across from the main entrance, they are twice the price)
Panera
Mimi's Cafe (Sign up for their email club and you will almost always have a buy one entree and two drinks, and get an entree fee coupon)
There are others as well, again it depends on where you are staying.