I have all 3 titles, yet still play on a daily basis.... U.T.
The only problem I have with U.T, is that the game servers you play on will usually flood you with ICMP for 3-6 minutes after leaving a server. This issue has been around U.T since version 4.00 (now up to 4.36).
The order I play these on-line games:
1) Unreal Tournament (T-O, CTF)
2) Quake 3 (WFA, CTF)
3) Counter Strike (play very little)
I am still playing U.T and Q3 because of all the available MODS. Currently I am playing the
Tactical Ops Mod. It completely changes the way one would usually play U.T, it's a lot like CS. As for Q3, I am playing the
WFA Mod and really like the type of characters you can play.
The best part about this is the fact that these are free mods, and there are many more to chose from.