UUC is the cheapest, then StopTech, then Brembo.
As for quality and performance it is the other way around.
The old saying "you get what you pay for" definitely comes into play here.
Sam at RennSport can get a great deal on the Brembos to make it a little easier to justify. If I were you I wouldn't be asking questions about the brakes, I would be trying to drive some cars with the brakes. Everyones opinion in here is basically based on what they have on their own car. I dont know many people who claim StopTech is the best but have actually driven the Brembo kit, or people who say Brembo is the best but havn't driven the UUC. Let us know what city you live in and maybe we can help you out by letting you drive our cars. There should be plenty of people here to help out.
I went to ButtonWillow and had the chance to drive Brembo, StopTech and AP all in the same day. I chose the Brembo.