How about really good hole in the wall Thai at Bangkok Taste, just south of the 22 freeway on Main, next to the Big Lots. (the street is Main south of the 22, and Glassell north of the freeway.)
There is a bit of an emphasis on Northeast (Isaan) style food on the menu; grilled meats, spicy salads, even sticky rice is on the menu. In my opinion this is where they excel. Many of their dishes are superior to the wonderful Thai Nakorn in Stanton, in my opinion, although their menu is not quite as extensive. (Nam Sod Khao Tod, for example.)
There are a few good places on Chapman, east of the 55. Super casual, but great food.
(1) Johnny Rebs' Southern Roadhouse
2940 East Chapman Avenue
Orange, CA 92689
I like the St. Louis Ribs and the sweet potato fries, but they do it right with much of their menu. And, service is efficient and congenial. Go and mess it up !
(2) Taco Mesa
3533 E Chapman Ave
Orange, CA 92869
Phone: (714) 633-3922
Sometimes, their specials are the best on the menu. My favorite on their regular menu is the salmon enchiladas in a creamy lime sauce.
And, another choice across town (maybe your preferred area) is
Cafe TuTu Tango
20 City Blvd W
Orange, CA 92868
Too much likings there to mention, but I may be including kudos for atmosphere.
re: kc girl
Don't agree on Tu Tu Tango -- not worth it... but your other two suggestions are spot-on. The taco alambre at Taco Mesa is worth the drive, and I love Johnny Reb's -- it's probably the best Southern food in the LA area.
In addition, there's Pepito's near the Block (they have wonderful enchiladas oaxacas, very good posole and quite good chile verde), there's J. T. Schmid's (brewpub gone slightly upscale) on Katella (technically across the river into Anaheim), there's good sandwiches and gelato at Caffe Lucca in the Orange Circle and of course there's King Harbor Seafood (technically in Garden Grove) and King Lobster Palace, Darya or Tulsa Rib Company, all on Tustin St. in Orange.
I really like Gabbi's, just south of the circle on Glassell. It's sophisticated authentic Mexican. Because I like spicy food, my only gripe is they hold back on the chili heat unless you ask specifically to scorch it up. That may not be a problem for others.
I think it's way better than Felix. Also slightly more spendy than Felix, but you'll know where your money went. Save a little room for the home made churros.
Just be aware the storefront might be hard to spot because they don't have signage. It's next to the Army Navy store.
Gabbi's Mexican Kitchen
141 S Glassell St, Orange, CA 92866
We fell in love with Gabbi's. The wait for a table is awful, and they are not cheap, but much of their food is phenomenal.
I had some of the best ever carne asada. If you have never had out of this world carne asada, you will be very surprised. The sauce is to die for. However, I do not recommend the shrimp that I had. Not bad, just not up to the standards of most of the menu.
re: Professor Salt