Comparing is honestly one of my biggest fetishes... I think it mostly stems from my own situation, barely 6" long when hard and as little as 2" or so when fully soft... Though I know I'm not small, I'm certainly in no way above average when it comes to length, and I love puttin' it up to the many bigger guys out there, admiring them and fantasizing what it must be like.
And to answer Kurious, from earlier... I know sex is different for everyone, but I would think that if one body part is bigger than another (almost anywhere in the body, barring hair and nails), and contains more mass of cells, would it not most likely have more nerves as well? There's no biological prerequisite (or research, for that matter) that says a dude with a bigger dick wouldn't enjoy sex or masturbation more than a smaller counterpart, at least in the majority of cases. It also may be a subconscious part of why huge ones inspire so much envy in the first place.