I use Gentoo. It takes me about 2 days to install (around 24 hours total time - I've got to sleep and stuff you know!) but for me it's well worth it. I've learned more about how Linux works and I have use of the wonderful emerge command so when I want something I can just type "emerge (program name)" most of the time! Not to mention everything down to the kernel is compiled specifically for my system!
My favorite distro for a newer person is Mandrake. It's what I started out on so I'm a bit biased, but the alternative, Red Hat, has a crippled KDE, doesn't include mp3 playing support, and various other things I take issue with.