We've got the always-excellent Rosa Mexicana a few blocks down the street for sit-down Mexican (and guacamole made right in front of you!), but for the quick chips-and-guacamole fix, it's difficult to beat Chipotle. The chips even come in a bag that says 'CHIPS'! For clarity of message, that hard to top.
And there is also general deliciousness! Now I want an afternoon snack already. . . .