Pancho Villa = prob. the best quality, although haven't eaten at El Farolita
La Taqueria is a chain of sorts but it's damn good
Cancun = mojado. that's all you need to know.
gotta check out the other spots...i'm in the heart of the mission, great places to eat there in general.
AFAIK La Taqueria only has one location on Mission around 24th or 25th or so, you may be thinking of somewhere else? Their burritos aren't the biggest and are the most expensive in the area, but their quality can't be beat. The carne asada and carnitas are both amazing as they only use the best grades of meat.. no spitting out pieces that are all fat and rubberized like you'll get elsewhere. And all of their other ingredients are top-shelf as well.. guacamole is chunky and pure, not any watered down imitation B.S, several types of amazing homemade salsas as well.
El Farolito is on the corner of Mission & 24th and is open the latest out of all Mission taquerias at the weekend. Line's out the door on a Sat night @ 3am. Pretty good quality and reasonable prices.
Mariachi's on Valencia & 16th is pretty good too, they've got this great mango salsa and some different untraditional flavors if you're feeling like that.
Agree on Cancun, you should try Corneta's mojado.
What I really miss is that place that served Indian Pizza right nextdoor to the Skylark on 16th. Indian Pizza @ 2am is the way forward if you're burned out on burritos.
WCB - Butter, the little dive bar in the SOMA? Hasn't gone gay, still as pretentious as ever though. Wish Bar around the corner is a better, more mellow scene w/o all the hipsters running around pretending they're white trash. And Holy Cow still brings in the bridge-and-tunnelers who still act like they're in college.