The savage is easier to setup for big air than the revo. The savage also allows you to install any BB engine (aftermarket). The revo really limits you on engine choice.
In general, the savage is easier to get aftermarket things for. There are things out there for the revo as well, but things like engine mounts, exhaust/header, clutch's, CB's, shocks... those are all very "revo" specific and most aftermarket replacements are pricey.
The savage will allow you to use almost any BB engine and exhaust pipe. With a few aftermarket parts, you can run 1/8 buggy shocks, different rims/tires easier, better engine mounts... stuff like that.
I have a old savage, but with many upgrades and a SH28 BB engine. I have a 3.3 revo chassis with a new era BB kit, but my pipe looks stupid.
Both are fun, but the savage was easier to upgrade and not have parts look funny on it.