Well, as the devs have said before, you should pick the Antag for the job., so while I agree Hans is spectacular on some maps, so is Kuzmann/Shae/Alicia. I can't see most of the others as viable Antags. And like I said, it's from what I've seen, as little as I've played lately, can't seem to get into a match on Xbox, like, ever anymore.
A smart Kuzmann takes advantage of AI movements, and his ability is actually really useful in CQC. Is he OP? No, but he is powerful when played intelligently, which you may not have seen done yet.
Do I think Hans is a powerful Antag? Yes. The best? No. He is so vulnerable while airborne to actual gunfire, any smart team just focus fires on him when they see him flying towards them. Konstantin is also a good counter (keeping him at arms length for his teammates), as well as Harec, who simply put, is the Antagonist Slayer.
But I definitely agree on that, far bigger problems than balancing issues.