Here's one list:
I'd say most of these are more hip than anything. I've been to many of them, and I can say they serve great food...with an effort for authenticity.
I wouldn't classify any as 'Tex mex', which I think is a whole different ballgame.
The question is:
What is Isn Smith's idea of a quality burrito? Then I might be able to direct you to a pseudo-rendition.
PS: Althpugh our schedules are probably the polar opposites, (eg. I'm currently beginning my work 'day'), I'm confident we can figure out a good routine. As spring/summer approaches, I reckon I'll have even more flexibility.