Where is the KingTiger, IS2, and Tiger on this Poll? The KingTiger is basically a super heavy as well. It would be nice if the poll was more inclusive.
Anyways, I think most of the heavies are fine, and they only need minor suggestions.
ISU - increase scatter perhaps, but I still think it can be countered since its fairly fragile
Elefant - rarely see this unit, but perhaps it suffers from "im not going to use this unit because everyone says it sucks!" syndrome.
Jagdtiger - just change it so it can't shoot through obstacles
You didn't put this on the poll, but I feel the best way to change them is to add more counters. Right now some tanks lack reliable counters like the Jgdtiger and KT. Their heavy armor makes it easy to brute force your way through opponents.
Elefant definetly sucks. Only usable as Maphack with spotting scopes.
70 range nerf was too much.
If you want to remove Jagdtiger shoot through obstacles ability, give it Spotting scopes, otherwise it will be such an useless unit without a partner with recon run, it will be as extinct as elefant is right now.