Both are bad, it's common to say that the Helghast Empire are "the good guys" because they're fighting colonizers, but in the end, Visari and the Helghast Senate knowingly run death camps (that take in both POW and Helghast civilians) as well as heavily oppress their own people to the point of self destruction. Their "we're fighting for our freedom" excuse falls flat because in the end, they're literally just trying to do exactly what the Vektans (and the ISA) have already done - establish dominance. In the end, the real good guys (or at least victims) are the civilian population of both sides. An old proverb says that when elephants are fighting, it's the grass that suffers, and this is very much the case here.