IMO it depends wut you are looking for Bottom, top, quality, price!All those have alot to do with which motor is better fit your need!first thing you should think about it before venturing into a BB Revo is your tranny and diffs!They are gonna take a beating.

bang for ur buck engines:
picco p3
Go tech
LRP

If you want the best:
Ninja
nova 528
RB 928