I just returned from a trip to California where I sampled a single cheeseburger at two different In-N-Out shops, a burger which is often wistfully compared, particularly by west coast transplants, to Five Guys burgers. For me, it was no contest. Five Guys wins hands down.
The In-N-Out patty was more regular and more compact, like it came out of a press. Five Guys is irregular, looks, and feels hand molded. The Five Guys bun tasted better and held the sandwich better than In-N-Out. The In-N-Out burger came wrapped in paper and needed it to stay together while eating. I didn't care for the In-N-Out sauce (I don't like mayo on a burger and that's the base) so I ordered the second one without sauce. I got a fully look, but they complied.
For me, it was no contest. This one goes to Five Guys, though I think that if I was taking a west coast visitor on a burger tour here, I'd have to take him to both Five Guys and Ray's.