A friend and I recently ate at Mama Chuy in DC and really enjoyed it - especially the sopes. I know you asked for MoCo, but I really liked this new little place and wanted to give it a shout out.

http://www.mamachuydc.com/

I like Ay Jalisco in Gaithersburg.

I really like Pollo Mex.

For Tex-Mex, we love Mi Rancho.

Samantha's is just meh in my experience.

It depends on what you mean by "Mexican." If you're looking for classic TexMex, Uncle Julio's in Bethesda does a pretty decent job. If you're looking for more authentic interior cuisine, go over to PG. We like La Sirenita.

Samanthas in takoma park, hands down.

Inspired by the Fairfax thread...