A lot of it depends how the server is setup as well. A default Vent server sounds just as bad as TS. But both can sound almost perfect. I do believe TS uses a lot more bandwidth for the same quality though.
At the end of the day it is really down to personal preference. I've been using Vent a lot recently after spending a long time using TS and honestly I've found Vent to be much better. It lags less, people have less problems with it, it uses less bandwidth and it almost always sounds better. TS looks prettier though! Thing is, if you ask another random person they will either entirely agree or say the exact opposite!