I remember the never-ending war between the Quake- and the UT-fans. It was hilarious. And both games had some true fans..I even remember people making Quake- and UT-tattoos.
Back then I played A LOT of Quake3 and UT99. I preferred Quake3 (because of the faster movement) while my twin brother preferred UT99. When UT04 (respectively first UT03) came out I first thought "well, this is much worse than UT99", but after playing it for some time I realized this game is also very good. Stuff like wall-dodging was awesome. I still can't decide which version I like more, I like them both very much.
If you think about it: It was actually very stupid to argue which of these games (Quake3, Quakeworld, UT99, UT04, Painkiller, Quake2,..) is the best because everything that came in the past 10 years was 10000000 worse than these games. Oh man, they were so fucking good...it's a shame they don't make games like these anymore :(
When GO came out I hoped it would be to CS 1.6 like UT04 was to UT99. But it's just worse in almost every aspect and comes with nothing new that improved the gameplay. Even Quake4 and UT09 were better successors of their games, though I also never liked them.