I am Mexican-American and my favorite food for as long as I can remember is enchiladas. Any kind, so long as they have plenty of cheese! My favorite way of having them is "flat," with a fried egg on top, and lots of lettuce, tomato and onion.
Something else which I like is chilaquiles, which is basically enchiladas, but without the meat. It is made with corn tortillas torn into quarters or cut into strips, and then covered with red chile and cheese.
A fun favorite of mine is Mexican hot dogs. They are made by slicing a wienie in the middle to form a pocket, stuffing it with cheese, wrapping it in a corn tortilla, securing with a toothpick, and then deep frying. Those are delicious!
Some other favorites of mine are tamales, posole with menudo, chile rellenos, fajitas, taquitos, and carne adovada.