well in terms of "friendships" I'd definately go for guys. It seems that we stick together for ages.
Most older people I know who are female dont see any of their high school friends anymore etc. The guys, ive found, are still mates.
Although, casual talking and hanging out with girls is swell. Especially really cool bubbly ones.
EDIT: Actually, come to think of it, i havent made many guy friendships at uni. More with girls. Partly because a number of my mates already go there. Secondly, a lot of the guys aren't really the type I'd be mates with. I get along with most guys fine (maybe not lebs. I hate those guys). I'm pretty likeable too. But in terms of my 'ideal' guy-friend (no im not being homoerotic) I haven't met many yet. Mostly jocks.