Wlad is already 34, so we probably have already seen his peak version, or we are seeing it right now. In 2001 was Wlad at his peak? He gave impressive beatings to Byrd, Botha, Mercer, McCline. 2006? That was after beating Peter, Byrd, Brock. I think this is the best condition of Wlad. 2009/2010? He schooled Ruslan Chagaev and demolished Eddie Chambers.
I'd say now. He is defensively better than ever, isn't getting any beatings in the ring, is supremely conditioned and won't decline for a while yet. Also coming off two techically perfect wins.
He is def. at his best and maybe still to get better, his power shots are unbeleivable and prob. has the most one punch power in the hit of the sport.
now. the wlad we see now is nigh on unbeatable, so much so people are starting to forget about his chin.
Probably now, but the last five years have all been brilliant. When was the last time that HW prizefighters, contenders, openly avoided a fight with the champ? Haye, Povetkin, etc. They see what happens to their peers, how badly they get dominated, and don't even pretend to want to get in the ring with Wlad (alright, Haye pretends, but that's all he does).
I'd say after the volume of amateur and professional fights and being stopped three times as a pro and all the wear and tear on his body, he's not in his physical prime. But he's probably in his technical prime, as good as he'll get and better than he was when he was physically fresher. Lennox Lewis was the same way. By the time he matured as a professional, he'd been stopped by McCall, had an extensive amount of amateur and pro bouts, had probably lost some speed, but he was better, more savvy, more in control.
Waldimir Klitschko is definitely fighting at his peak ability right now. Aside from his brother - there seems to be no one out there with a real chance to stop him.