I had never had In-N-Out until about two years ago, and I must say that I was impressed. Tasty burgers and I like the fries although many seem to love 'em or hate 'em. The shakes are also pretty good.
Here in FL we've recently been blessed with a franchise known as Five Guys Burgers and Fries from the D.C. area. Its not exactly fast food as there is no drive-thru and the two we have here are located in strip malls. That aside, they have burgers and fries that rival In-N-Out IMO. My fiance' is hopelessly addicted.
Craig