I think Savage is super sweet as well.
I'm probably gonna skip going over Rad Armor. Everyone loves it and it seems to pair well with everything. IDK if there is any particular synergy there with Savage, although I'm sure it'd be an amazing combo.
Shield/Savage would probably feel SUPER mobile with both Charge and Leap. I like the idea of being able to move from group to group so quick.
Dark/Savage seems like a VERY thematic concept and to have the most direct synergy, IMO.
Elec/Savage to me just seems like it would be absolutely no fuss, no frills. You just mow things down and keep going.
With all this in mind, I'd probably go with Dark/Savage myself. Dark Armor can be a pain to level, and Savage Melee helps with that. Once IO'd out, Dark Armor is amazingly good and Savge Leap will really help you get into the thick of things.