Smashburger is a good burger alternative to the In n Out next door. Think of it almost as a somewhat higher quality In n Out. They have a pretty extensive menu with chicken burgers and their regular burgers. Also, you can build your own burger. They also have a number of different sides and shakes.
I like to get the Sin City burger, which has onions, egg, smash sauce, and bacon. Top it off with a side of smash fries and you're set.
They are a little bit on the greasy and pricey side, but this place is a pretty solid burger joint.