El Sol near Danforth and Greenwood is very good, but consider ordering 2 hours before you arrive, the service is awful (slow and chances are you'll get the wrong thing when it finally shows up).
The one in Kensington is "Mexican Salsas" and it's a taco place, pretty good and not expensive. La Tortilleria is also good for tacos (one in Kensington, one on Dufferin at Bloor, and one on St. Clair West).
Milagro is good and relatively upscale, there are a few locations. Dos Amigos is good for queso fundido and a decent brunch, but I think it's overpriced. La Mexicana, I haven't been there for years, for a long time it was being run by Philipinos and the food was pretty bad and expensive.
Best in town is in Kensington Market, a food stall in one of the empanada places, run by a REAL chef named Francisco, it's take-out only and the long line-ups are there for a reason. I shit you not: BEST MEXICAN IN TOWN.
My favourite place is actually a Salvadorean place than serves quasi-Mexi food, but I don't want you all cluttering the place up, it's busy enough as it is!