If you are hosting it yourself, TS would be the better option if there are quite a few of you because on the free version you can host up to 30 (may be 20) people, which is a lot more than vent allows for. You also don't get the sounds when you want to talk or when someone leaves or when some other crap happens, you only get told when people join/leave.
It is also much more easy to admin I have found than vent is, and much easier to join and set up favourites and what not.
I've used both extensively and honestly, I can't find anything that would make Vent better than TS