If I had to voted out of those options, it would be Burger King, because McDonald's is just okay, never had Sonic, and In n Out doesn't exist here.
However, I'd put Five Guys and Harvey's at the top.
I feel really bad for the guys on the east coast, because they have never had an In N Out Burger
Denver just got a new chain (started here in Denver) called "Old School Burger" that is like an in & out, but better IMHO.