Linux

Arch has lots of precompiled packages in a repo and a really good package manager - pacman. But it is also really easy to compile your own packages and install them. Arch has the AUR - Arch User Repository - where you can submit your own build files. Others can download and build their packages according to that.

I liked arch but the Arch Build System I was always too thick to figure out. I prefer ports on the BSDs, just make install clean.