Rather than starting a "which is best" thread, I wanted to just create a thread for people to review burrito / taco joints in general. I've now tried a fair number, and here are my impressions.
Burrito Boyz / Burrito Bandidos
Unless I'm missing anything innovative at either of these chains that distinguishes them, I'll treat them as one. As I have said before, I consider these among the most overrated restaurants in town. The meat is bland and the salsa comes out of a giant industrial jug. Service is indifferent at best. The tortilla is grilled instead of mission-style steaming (I prefer grilling), but sometimes grilled to the point of burning. Basically, this place has stopped trying because the masses keep paying them whether they are trying or not.
To some up my experience with mission burrito in one word: salty. In two words: salt and cumin. The chicken, beans, and rice are heavily oversalted, and the pulled chicken has way too much cumin in it. Which is too bad, because otherwise all these ingredients are well prepared. It would be easy enough for MB to switch to a traditional tinga preparation for the chicken. The pico de gallo is fresh. The hot salsa doesn't deliver much heat or flavour. The lime-cilantro sauce is tasty enough, but seems to cater to cilantro-phobes by overdoing it on the lime. Fresh cilantro and lime wedges would be better. Yes, MB steams its burrito in true Mission style. One more thing - when I went, the tortilla chips were rancid, presumably from being left in the warmer all day. Because of the salt issue, I won't go back . But with a few easy tweaks, MB could have the best burrito in the city. So-called tacos are actually made with wheat flour tortillas (as opposed to corn).
I've only had the tacos here. The meat was well seasoned. I had the cochinita. The other fillings were standard, I don't really remember them. I remember getting guac at no extra charge, but don't think I was supposed to. Unlike a lot of burrito places, they use proper soft corn tortillas for the tacos, which they also steam before a few seconds in the convection oven. The hot sauce is a liquid taqueria style sauce, apparently habanero-based. It provides heat but not much flavour. There is no salsa roja. I will go back if I'm hungry and in the area, but wouldn't make a special trip.
What I like about Chipotle is the quality and freshness of the ingredients. On the other hand, the meat lacks flavour, as do the beans and rice. The other ingredients are generic and the hot salsa is pretty tasteless. The pico de gallo seems to be made fresh in store. I go here often when I'm in the area, mainly because it's healthy, fresh, and the ingredients are good. So-called tacos are made with wheat tortillas, not corn.
Mexican Salsas (on Augusta)
I've only had tacos here, and I've tried most of the meat fillings. All of them were well seasoned and delicious, although again there is an issue with oversalting some of the meat. The only real complaint I had was that the salsas were kept warm on the warming table, which changes their flavour profile and consistency somewhat, and not for the better. On the whole, though, the tacos here were good, and the price incredible. (Toronto Life also loves their burrito).
The food kitchen in the back makes tacos, pupusas, and tamales. i've had the tacos al pastor, a bean and cheese pupusa, and chicken tamal. While not a true pastor - nowhere in Toronto uses the spit to make the pork for al pastor - I'm generally satisfied with the seasoning of the pork (and pineapple), which is basically pan-fried. Tuesdays and Wednesdays they are 3 for $6. The tortillas are heated on the griddle, the salsa is hot and flavourful, and the fixings generally fresh. The pupusas are good (not really a fan of pupusas though), not surprising since the owners are Salvadorean. As I recall, the tamal was not bad, too, though it was a while ago I had it - certainly worth the price.
Tacos el Asador
This Salvadorean place was a lunch mainstay for me for quite a while. It's cheap and the food is fresh. The salsa served on the side is hot and it's nice that they always serve jalapeno and onion relish. I've had bean tacos, pork, and chicken, and there really isn't much to write home about in terms of seasoning or preparation of the fillings, which are pretty rustic, but satisfying.
La Tierra Azteca
Come in here on weekends and the place is packed. Most staff do not speak English, and neither do a lot of customers. Most of the clients appear to be coming for the pancita, pozole, barbacoa, and carnitas. I tried the carnitas. The meat was tender but lacked the crispy finish a lot of carnitas has, which makes for an interesting contrast and richer flavour. But with the fixings and a delicious red salsa, and plenty of tortillas, the meal was quite satisfying. You can also get gorditas. There are also arrachera tacos on the menu, but no burritos - the clientele is almost exclusively Mexican and not interested in burritos.
By far the best budget taco place I've tried in town. I've had the enchiladas verdes, most of the taco offerings (cochinita, chicken, chorizo, chorizo con papas, chicharron en salsa verde), as well as the huarache and sopes. Everything is uniformly excellent, and better than anything downtown. One thing that might be improved is the refritos, which could use more flavour (lard or garlic, perhaps). No burritos on the menu here, only food that is recognizable in interior Mexico.
Some places I want to try: Hoy Cena Pancho, El Taquito.
One notable absence from the burrito joints is chile verde, which is delicious and easy to make, and a ubiquitous offering in taquerias in the US.