Well, everyone seems to like the mach .26/sportwerks .26 and the hpi .28...and the wasp .28, and then there's the new OS 30 coming out...
powerwise, here's how the engines go (from least to most):
sportwerks/mach .26
hpi .28
Wasp .28
OS 30
the sportwerks and mach and hpi .28 are pretty much the best engines for racing in the savage.
O, and the fantom .28 should be coming out soon too...