I've played a few, the most recent being Unforgiven which you need a source port and super computer for if you are using Dark Places.
I played requiem and KQP (killer quake pack) ALOT on the original id levels agains the Zeus bots and Reaper bots-many many hours of game play.
And...spent alot of time playing Quake Rally. Now that is my favorite TC of all time. I remember waiting for it to be released back in 1997 and played the living shit out of it. In fact, we played it a few days ago on two Pentium 1 computers in LAN with Win98. We warpped to the cult level and played for a long time.
Never did get to play the mission packs. That is on my bucket list Also, I used to play Navy Seals Quake alot, awesome weapons.