Ventrilo is better. Simply because of this:
1. When someone joins the server/channel you get a message like: God a.k.a NoSNo has connected (:P)
If you are playing a game and you hear. Guest/member joined i always want to know who exactly it is. So i know who im talking to.
2. It isn't as laggy as TS
3. Ventrilo has a better sound quality

I use both ventrilo and ts. But i still like ventrilo best. (probably because that was the first i ever used :P)