Depends what you want it for. I've used Waves plugins in the past, and the only one that I went back to time and time again was the SSL E-channel - I'm not really one for mixing etc... in the box, but that particular plugin just sounds brilliant. The SSL Buss compressor is also a handy thing to have.
Not really had much experience with the T-Racks stuff, so can't help you there. Sorry.