The best game imo would be qwtf (quakeworld teamfortress) yes yes i know its a tad old
but the community is running along pretty strongly with kickass new graphics (on par with atleast quake3).
I suggest you check out
www.fuhquake.net and qwtf.ausfortress.com if you feel like a hell fun, fast passed rush
Due to me being in yr12 this year, i've kind of left it dead but there's still heaps of people that play regularily, it's a bit surprising