Eh, I like Chipotle.
Comparing it to authentic Mexican food seems a bit silly just like comparing Olive Garden to true Italian food or PF Changs to real Chinese food. Or for that matter comparing giant, sauce laden, tempura containg, inside out American rolls to authentic sushi.
Then again I don't generally get burritos or tacos at Chipotle. Usually it's a steak bowl with brown rice, fajita veggies, black beans, mild & hot salsas, cheese, a touch of sour cream and as much lettuce as they'll give me. Not a bad lunch.
I can understand someone subjectively liking the taste of Taco Bell more but the difference in food quality is pretty stark. Chipotle is pretty transparent about where they source their ingredients from, especially their meat. TB on the other hand uses the lowest grade meat possible or at least they did a few years ago when I looked into it.
Now if I actually want Mexican food there's countless unbelievable options. For my money California (both Bay Area and SoCal) have better Mexican food than anywhere else - including Mexico. At least what we think of as normal fare. Once you get past the northern part of the country the cuisine changes significantly and is awesome in its own way, especially the Yucatan, Oaxaca, Sinsloa & Veracruz.