With today's suppressors, it's not really about decibels anymore. If there were a line-up of all the most popular suppressors, there would be little-to-no difference at all in what you hear. With that said, I believe it mainly comes down to feature set and reliability. I can say that there has been quite a few issues with the Surefire QD brakes in the past (mine included). When shooting with only the brake, the precision goes out the window. However, when shooting with the can on, it's right back where you need it. I'm not sure if you have tested yours out before or not? I do love my brake, though.
I would simply pick whichever one you like better and know is reliable.