I don't like very late nights as I get way too tired for my liking. I think I'm getting old or something - I tend to go to bed between 11pm and 1am lately, sometimes onwards towards 2am, but not often. I don't like getting up early normally, but if for some reason I've gone to bed early and wake up (out of bed) at around 5-6am, I must admit it is quite a nice feeling to be up for a long day... provided it's the weekend. If it's a workday, getting up is a chore no matter when you do it.

Overall: Late nights have the edge.