1 UT2k4
2 UT2k3
3 UT99
4 UT3
My opinion is identical to that.
We all know the first UT was probably the most played of all, but that's back in the 56K days. It's also the first to the franchise and quite honestly, did deliver for ages. The netcode is simply put, horrible.
UT2004 was the most online-satisfying game I have played in my life. The game also had a quite long lifescale. With it's own inconvenient, it eventually became "Exploited" in therm of knowledge. This also occurs to every games on the market, of course. Some games tend to live longer than others.
UT2004 being the "Hitscan" dommnance, and how the game eventually turned into "TAM" fest. For some reasons I really ignore. Most of the people found the vanilla gameplay boring. Probably because they couldn't handle item management, such as timing and picking up weapons constantly after dying.
Timing was the most annoying thing I have seen in the last pubs I played. I'm kind of competitive, but I have my pace, and I certainly do not wish to time power-ups like my life depended on it
"Play to win, PLAY TO WIN!!!" - It's a public server, I only wish to frag and have fun.
I find decent players who time power-ups on remaining pubs complete idiots. But that's just me. 1v1's seem to be more fit for that.
UT3 was simply, completely wrong in many levels. The actual level desing, and weapon design made the game completely unfun for most of us. Take Shangrila. It has open/narrow spaces (rocket area anyone?), and ETC. The kind of layout I'd see in Call of Duty, and the actual weapon balance punished snipers in actual DM/TDM play, rockets were completely easy-to-use and lethal. Even though the game had custom content, people weren't bothered with the gameplay. I also recall a few issues here and there with the map redirect system.
It was actually hard to see their direction when you look at the DM/TDM play. Warfare (Onslaught 1.5) was probably the best design this game had. But then I still see a lot of imbalances.