You know what my choice is

FreeBSD, for it's brilliant ports system and excellent stability (that includes API/ABI stability).

Must have applications?

Firefox - 'cause we need to troll forums
Pan - Still use usenet (Pr0n obviously)
Gimageview - we need to be able to watch
Mplayer - See above
Vim - because I need to edit a config file or two
tmux - terminal multiplexer, don't leave home without it
ezquake - to frag away the stress
blender - someday I'm going to understand it
tsclient - nice frontend for rdesktop
rxvt - we need something to type those commands in
transmission - nice P2P client, can run headless on a server

I'm sure I'm using more but this is just from the top of my head.