Debian is teh win!
I've been playing with other distributions recently, under Xen, and so far I have to say that Debian is sooo much easier to work with. (And not just because I'm more familiar with it).
Gentoo: Portage does rock, but damn it is slow. I don't mean the recompilation, because you'd expect that to be slow, but something as simple as "portage sync"; takes minutes to complete, and pegs the CPU whilst it is running.
A similiar story for CentOS 4.x - the yum tool seems to be one of the slowest network applications I've ever used! Updating the lists of available packages is just painfully slow, far too much "thinking" between the download operations.