None of them?
After watching even a little bit of Gundam and/or Code Geass, the mechs featured in this movie were incredibly bland. Their primary mode of attack all seemed to be "punch things ineffectively," and only when shit got serious did they pull out their 1 (!) unique weapon, like a titty missile launcher or a zap cannon. The most "unique" themed mech was easily the chinese one, and they did *nothing* with the fact that it had 3 arms. Mount an arm on the chest, mount an arm on the torso, mount a long arm on the back and have it reach over the shoulder or under the legs or something; if you mount an arm behind another arm, so that it gets blocked by said arm any time you actually fight anything, the arm is
totally pointless (as it was in the movie, the moment they came across a monster with a tail-arm they got their shit wrecked).
I was just put off by the lack of mech diversity. They look a little more unique than, say, anything from Bay's transformer snorefests, but given their origin in various manga/anime, they were unfortunately all very similar.
Just for a small preview of what could have been drawn from:
The Epyon whip-chain-sword that Gipsy Danger pulled out was badass on several levels, but that was really the only moment I was "wowed" by anything the mechs in the movie offered. It seemed more sensible than they'd all have some kind of "weapon," even if it was just a giant sword or lance or tail-mounted flamethrower. Yknow? Even when he just picked up a ship and whacked the bad guy with it, it seemed to be far more effective than the silly punching they did for most of the film.