Answer: The one that you own.

A buddy of mine has the ViperTec, he loves it. It's quiet, smooth, all that. But then again, so is EVERY Hoyt made with the Cam 1/2. The Trykon is good, but it has it's downfalls. The drawlength isn't adjustable and IMO they are stiffer to pull. BUT, they are great bows.
Personally, I would have to say that the UltraTec is as good as it gets. But, it's longer ATA, and that may not be for you. There are lots of factors that go into which one you want.
The best advice I can give, go to the pro shop and shoot every one of them hanging on the wall. One of them there will fit you better than all the rest.