HP laptops tend to be bigger in size. Though now, I believe they're cutting down the sizes and increasing the performance.
Personally, I would go with HP laptops. I have an HP laptop, and it's great - though I have one of the bigger models. I mean, Dell laptops are decent, too. I have a friend who has it, not a problem at all. It's a matter of preference/what kind of deal you get. If you were to talk about desktops, I would say neither, and I'm guessing at least 99% of the people here at TF would agree: the best way to go is custom.
---- If I had a choice, I would probably get an Apple or IBM laptop, but that's just me.