I own both games as big box copies and played both back then

Quake 3A´s movement was abit better than UT´s, but it was inferior in every other category:
- Game Modes (UT had more variety & mutators)
- Maps (had alot more good ones compared to only a few on Q3A)
- Weapons (UT had more weapons and altfire modes)
- Music (UT is miles ahead compared to Q3´s tracks who all sound the same and are pretty forgettable.)
- Mods (UT had a gigantic modscene compared to Q3)
Cant deny the facts