Bellew v Haye at cruiser both in their prime who wins?

No, I'm not saying that. But they do have to have a record of being tested more than a couple of fights against reasonable 'live' fighters.
A few months ago plenty of people here were saying Chris Eubank Jr, clearly passes "the eye test" but that's very disputable now.

Haye proved himself against Mormeck at cruiserweight but also has a loss to Carl Thompson. A couple of other good wins and that's it. He was proven to some extent but not completely enough to say he was great or dominant in the era.
At heavyweight he's done very little. Nothing to justify the reputation he's acquired. The title he won at heavyweight was a paper title. He looked awful against Klitschko.

Mike Tyson beat a whole lot of contenders, far more than Haye, but was beaten up by Buster Douglas. You have to rate him accordingly.

Calzaghe has a weak resume but he was dominant for years and never lost.

Every boxer is a different case. I'm not saying Haye has no accomplishments. I'm just saying his reputation and rating has been inflated somehow.

 

Within the landscape of what the cruiserweight division has been and is, he surely must be thought of a 'Great Cruiser'. If you want to argue about all round p4p great, then yes you have a barrel full of ammunition.

 

Absolutely - Haye will always be remembered as Le Toe

 

Is this prime Bellew right now?

 

Not being able to KO Eubank is not exactly a criticism of a fighters punching power. Eubank is regarded as one of the toughest SOBs British Boxing has ever seen. 25 of Thompson's 34 wins were by KO - a KO ratio of 73%, thereabouts - so it's fair to say he had decent power at the weight.