In my opinion hands down Gonzalez's there's two locations: East Dallas and Oak Cliff. When I go I usually go to the Oak Cliff location.
The food is great, but their niche is probably their homemade flour tortillas; they are seriously as thick as pancakes. Also I'm not a big fan of enchiladas, however, this is the only place I will eat them, they are great.
Just in case, if anyone really likes tamales, you all should try Tia Doras Bakery also in Oak Cliff. These tamales are as thick and big as some burritos you purchase at some mexican resturants; and they are not greasy at all.
Veracruz. Two locations...one in Cedar Hill and one in Dallas, I think. Entrees you won't find any place else. The Pescado Xanath: white fish fillet stuffed with shrimp and crab with Crema Totonaca...blue corn enchilladas, fish tacos... shit, just drooled on my keyboard...
Some listed on here I might try, though.