I have already beaten the campaign on the side of the NCR, im playing it again except this time for Caesers Legion, which companion wud be least offended by doing evil stuff?

Lily doesn't care if you roll with the Legion, nor do either of the non-humanoid companions (Rex, ED-E)

dang is that the only humanoid type one?

Never tested Raul, but I don't think he'll care. I worked with the Legion on a few side missions, he was sarcastic but helped anyways.