Chimera fairly easily. In fact, in truth, outside the fact you have to 'win' in the games, it's pretty obvious that playing the 'what if' game the Chimera would have easily mopped up the Earth with their technology vs that indicated of the remaining humans in the game.

Chimera's superior technology along with DNA morphing easily destroys puny helghans

Chimera would surely win though I wish that the Helghast would...

It's like the question "Who would win in a fight - Kratos or Mario"

It's obvious that Kratos wins, but Mario would still get a ton of votes. (loyalty is the keyword here)

Now I can understand that this thread isn't THAT obvious, but yeah we already got some pro Helghast votes just because they look cooler....