Brushless revo: 3905 tranny or revo tranny?

I'm building a brushless revo out of spare parts I have. It'll have the 3.3 chassis. As I don't have a tranny yet I was wondering which option would be best and why?
-Emaxx 3905/Erevo tranny?
-Revo 2 speed tranny (and then locked in second or not, forward only or not)?

I don't want mechanical brakes, and plan on using 2 3s lipo packs which I will also be using in my G2R revo.

Any advice would be much appreciated.