Best burger is either Chilli Willie's in Arroyo City or Salinas' in Donna.
The White House in Raymondville is old-school home cooking.
Blue Onion in Weslaco does some good original food. I like Milano's, also in Weslaco.
Las Vegas is good for Tex-Mex in Harlingen. The Tex-Mex Grill in Harlingen is also good, lunch only, I think.
Guerra's in downtown McAllen is a nice white-tablecloth restaurant with good food.
You need to refine your search options, though, because I could name 25 taquerias, several Chinese places as well as others to this post.