Never been to Fatburger. I did go to the original Tommy's once, after a Dodgers game. Absolutely brilliant. Of course, that was long before I'd heard of In-n-Out or cholesterol.
And I live 1 1/4 miles from the nearest InO. And 3/4 of a mile from the nearest Starbucks.
One of the Tommy's, on Sunset I think, was about a 15 minute walk from my high school. We'd head there now and then for the chiliburgers. Man, one of those was a project.