Mexican food encompasses a vast range and what's considered "good" differs by region even within the US. SoCal vs. NorCal vs AZ vs NM vs TX... depends on one's expectations. So take this with a big gain of salt
AMANO is in a class of its own. Upscale and unique.
For family style sit down we've had great meals at Andrade's (Overland Rd), El Mariachi Loco (Star), and Casa Mexico (Hyde Park).
Good basics: Carniceria Coalcoman, Tacos El Rey, Taqueria Las Brazas, El Chavo
White people resort style: Parrilla Grill and Tin Roof Tacos
These are just a few of the places we've liked in the Boise area, lots more in Nampa and Caldwell that we haven't explored, but my sense is that the Mexican food overall is better in these areas.
ETA: The other day I drove past Lorena's Mexican Grill on Fairview and it looks like the kinda hole in the wall place I love. Haven't gotten around to trying it, interested to hear if anyone here has been.