Best food in Anaheim and L.A.?

My buddies and I are going on a road trip to Cali (from Louisiana!) over the Christmas holidays. We know people in Anaheim and Los Angeles so that is the intended destination but we’ll probably veer here and there along the way.

What are the best fast food and sit-in restaurants of California that you know of? Any random favorites not many people don’t know about? What are some fast-food chains home only to California?

(side note: I was pretty impressed when I had In N Out Burgers for the first time).