I felt pretty even about UT and Q3. Q3 had the snappier and more precise feel, and an aesthetic I preferred slightly over UT. UT seemed like it had more to offer in all other areas though. Since I didn't play that much online, mostly just bot matches and 1 on 1 vs my brother, I let him decide which to get. We couldn't afford many games at the time, and bought one copy to share between us. Of course later I endd up getting Q3, but still never played much online.
That's actually something I don't hear a lot of people say though, that they typically play against bots when they don't have friends to play with. I really don't like many competitive games online. People get bitchy and angry over the dumbest things, are low-lifes in general, and have likely spent thousands of hours more than me practicing this ONE game, where I've spread myself thin by playing others too and can't compete. I did get really into the competitive multiplayer in Modern Warfare 2 and Black Ops, but they both started to leave a bad taste in my mouth after a while. Lately I stick mostly to cooperative stuff with people I know.