Gentoo has been the best for me but it can be a bitch to install (time wise), took all day on 1 system and 2 days on another. good thing about gentoo is you dont have to worry about wating on the next version to come out. if u want the lastest gentoo:
emerge sync
emerge -u world
edit:
the reason it takes so long to install is becasue you compile everything from source code (starting with glib and the compiler itself). You can install from a CD and skip the compile process but it kinda takes away from the whole point of going with Gentoo in the 1st place.
http://www.gentoo.org