Never had the opportunity to eat at an In-N-Out, but I have eaten at several 5 Guys burger joints here in the Philly area and I have to say that I really love them. Best $5 burgers around IMHO. Their fries are delicious as well. Bottom line is that we all enjoy something different, which isn't a bad thing.
On a side note, Emeril's just opened up a specialty burger restaurant in one of the local casinos. Some friends highly recommended that we try it. At first I was shocked to see the price-$14 for a burger, but you could top it with any a ton of different toppings and it came with a huge order of fries or onion rings. Best burger I've ever eaten, it literally melted in your mouth, just delicious. Not sure how many calories, I don't think I want to know.
That being said, thanks to In-N-Out for all they do to for our sport, much appreciated. I will definitely try one of their burgers if I find one of their shops on my travels around the country.