ET is still a top 5 multiplayer fps game. It's obviously less popular than CS and CSS, but it's playerbase is about the same size as cod4 and battlefield2. Recently pub modes have been gaining more popularity than etpro but there is still a lot of competition- just look at CB OC signup list or number of random cups etc.
Currently a new competition mod is in developement. It's basicly etpro + anticheat module and will probably replace broken PB.
As for ETQW or recently released Wolfenstein- they are dead. ETQW got better with each patch but when game started to be playable it was already too late. Most people got discouraged with early builds.
Wolfenstein is a console port and you can safely just ignore it. Player peak is about 100-200 people at any time. That's a terrible result for a game that has just been released. There is a competition mod in developement but the game is fucked beyond repair.
I I did a little gamespy search and saw that is looked quite strong - even after all these years.
So I may just forget about my Quake Wars key, and play ET or Battlefield 2 which I also have, but must track down the CD key or buy again. I lost that key too.