Before any of the gents here tell you to search, allow me to provide you with something more substantial.
I've heard the SPT, Magnaflow, and the Nameless axelback with magnaflow muffler.
My personal opinion, in terms of drone, rumble quality, and finish
Drone (highest to lowest)
Magnaflow (almost none)
Rumble quality (at idle, highest to lowest)
Finish (best finish, welds, etc)
Magnaflow (pretty bad once you start looking for details, but if a person is simply standing behind the car, they're fine).