Ive got the AEM and its very nice. I think the AEM also dynoed the most HP aswell IIRC
+1.AEM, Injen & CP-e on the only three that I would run, but everyone has thier own opinions.
I also chose CP-e for different reason....needed the room behind the bumper to run my front brake ducts, so not enough room the AEM CAI.+1.
Personally I picked CP-e, because I have plans to run all their hardwares, and their parts are upgradable (for example, the intake and the downpipe can be reused when they release their turbo upgrade; you just have to change the silicone pipes).
Unless your going cai, most of them will dyno the same + or - like 2hp.
I would be surprised to see anything more than 6 or 7 wheel hp MAX from a CAI (as the only mod) on the 2.0T and you may even be losing torque with a CAI with all else stock.