Since you're So Cal based, here's a few of my tips for places to try:

Chipotle is not one of my favorites, some people rave about it. It's under the parent company of McDonald's. I'd rate it at the bottom of my list, everything seems seasoned improperly.

Baja Fresh is good mostly because I like the salsa bar. It's parent company used to be the same as Wendy's. I'd rate it in the middle of my list.

FINS is good, but used to be better and they closed many locations. I'd say they have one of the better fish tacos. K-38 is my choice of meal. I'd rate them closer to the top of my list.

Wahoo's is good, but big on piling on the beans and rice-less, small on the entree. To me everything besides the fish taco is good here. I'd rate it closer to the top of my list as well.

La Salsa is very good, but seems to be on the pricey side. Their salsa bar is good and menu selections are decent. I'd rate it near the top of my list.

Taco Mesa is excellent. They have creative menu items that taste authentic and the only thing I don't like is they are only in Orange County. Probably #1 on my list, worth the effort to go to this place!! (Plus they serve beer!!)

Rubio's is good, fairly consistent, better are the fish tacos compared to most of the rest of the menu. I'd rate it somewhere above the middle, but below the top of the list.

Sharky's is my current pick. They serve Organic food and it tastes good (especially the brown rice if you can believe that). Limited locations, but they're fairly new.

Speaking of favorites, there's a place on the web to visit that I like to check now and then for restaurant picks. Give it a try: Chowhound