I agree that the STZ is one of the best tanks around that BR, if the STZ is your play style, then I'd recommend the KV-1S. It is a heavy, however for some reason the KV-1 series have amazing mobility and speed for heavies. It can be used to brawl nicely as it has good armor, especially the turret. It can also flank & get into good positions with its speed and mobility. It also has the same gun as the KV-1 ZiS-5.

Keep up on the T-34-57. Of all the lower tier T-34s, that is my favorite. It works very well even in an uptier due to its pen. However, when I used to play AB that thing was an assist machine, in RB it is a killer.

If you're wanting to move more in the direction of flanking w/o the CQ brawling, the ASU-57 is good. Well, can be.
AB - Crap
RB - Good
SB - Amazing