I have had In-N-Out. I like Whataburger better.
But then again, I got to eat from the first Whataburger opened and that pretty much set my preferences in motion.
My second favorite was the A&W drive ins. Frosted glass mugs full of fresh A&W root beer. And those burgers. I dunno. Maybe I am waxing nostalgic, but that was some good stuff.
NB introduced me to my 1st Whataburger at the last con ... had to admit is was quite tastly !!!
A&W !!! ... did the car hops have roller skates on ? ... our local A&W, when I was a kid, had the roller-skating car hops and your food was delivered on trays that hung off the windows. Their root beer was the best I have ever had ... bar none.