Berbick has some bad losses, true. They all do. That's why it's difficult. But he didn't "almost lose" to Ali. Berbick lost one round (out of 10) on two of the cards ... on a show staged and promoted by The Nation of Islam.
Other than head to head, I think the only way to rank them is on balance of their best wins against their losses. It's not easy as the results defied boxing arithmetic a lot of the time. Witherspoon would be the pick I'd feel most comfortable with, but I totally get counter arguments to that. I'd tend to use Holmes' and Tyson's reigns as dividing points for the period. Tucker and Douglas to me were late 80s/early 90s heavies, rather than the rest of the pack during the Holmes era.
Not sure about him being on top, but Weaver definitely deserves more credit than he usually receives. Gave peak Holmes an incredible fight, including a knockdown. Beat prime undefeated John Tate one punch, then pretty much did the same against a super hot Coetzee. Broke Tillis' undefeated record. Got robbed twice against Dokes...I had him 3 points ahead in their second fight. One punch knockout of top tier contender Carl Williams, gave champ Thomas more than a little fight when he (Mike) was already kind of past it. Not sure this ranks him ahead of Witherspoon (who quite likely was at the top of the heap at this time, though he never quite seemed to reach the near-dizzying heights of the Holmes fight again).
I like Weaver and think he was the most consistent of the lot, although he lost more than he won against the other ‘80s champs, but I can’t make the leap to him getting robbed in the first fight with Dokes. He got knocked down in the first round. He got up and laid on the ropes while Dokes threw like 25 unanswered punches while Weaver laid on the ropes, with Dokes landing most of them (not all were clean but many were). He didn’t throw a single punch back. There’s an argument to be made that Joey Curtis stopped it too soon but there’s a far better argument to be made that if Weaver is indeed OK, he should have thrown back, or clinched, or done something except lay on the ropes like a heavy bag. A referee cannot read a fighter’s mind, and if he isn’t fighting back after being knocked down with double-digit punches raining down on him then how is he supposed to know if Weaver isn’t hurt? Should he wait for another 25 punches, or 100? The ‘robbed’ implies that if not for the ref’s actions, Weaver wins. It’s a short fight but Dokes dominated it even before the knockdown (Weaver landed two or three good shots to several by Dokes). There’s no world where someone can watch that fight and and say ‘well Weaver got robbed, that was his fight and they took it away from him.’ As for the rematch, all I can say is that it’s sleep-inducing. Maybe Weaver deserved it, maybe not, but I can’t see getting on a soapbox about a fight where neither guy fought that hard to argue the outcome.
I probably exaggerated some on the first Dokes fight, however looking at Dokes' later performances I'm not sure he would have won had Weaver been given the champion's benefit of a doubt and continued. Dokes...well, he really wasn't ever particularly good, was he? Iirc his greatest win was Weaver...I saw that fight the day it happened and I and every boxing friend I had thought it was stopped too early. But of course, hindsight is 20/20. He took more than a couple really good shots (I'm not sure any but the original knockdown punch were much more than arm punches, though).
Weaver got hit with a beauty of a hook that turned him sideways and went down on the follow-up punch(es) I think but it wasn’t a flash knockdown — he was definitely hurt and out of sorts, and with him covering up on the follow-up Dokes was definitely loading up and some got through with real force. I’m not going to lay blame at the feet of the ref if a guy isn’t throwing back or moving off the ropes or trying to clinch or … anything other hand holding his hands up when a couple dozen shots are being put on him after a knockdown. He got up and never moved off the spot when Dokes waded back in to try to finish him. I have to put that on Weaver — if you’re OK, do something — anything — to make that clear to the ref. That aside, you’re right about Dokes. I kind of lump him in with Greg Page — probably at some point either could be said to be the most talented and have the most potential and ‘looked like’ the heir apparent to Holmes, but neither lived up to that potential. Far too inconsistent, whether due to drugs in Dokes’ case or all-you-can-eat buffets and general laziness on Page’s.
Tucker? What the heck? He hadn't even looked like fighting a top 10 contender by the time Holmes lost the rematch and retired.
He started his career 52-2 with competitive decisions with Tyson and Lewis and beat the guys who'd upset them. To top it off he won the USBA/NABF double and the California title. Given how inconsistant everyone was in this era the padded resume gets more mileage.
Tyson and Lewis were after the Holmes era. Tucker spent most of his career fighting nobodies. He beat one single contender in the entire 80's let alone the Holmes era which finished in 86. You are likely the first person in history to label the USBA/NABF as a "double". These titles and the California title were hardly massive achievements. You've got to know Tucker or be related. This stuff has been explained to you plenty. Tucker has one truly significant win in his career and Douglas dropped tools after being even in the fight up until then. Truth be told he'd looked the more impressive.
Lewis beat Tucker by the scores of 118-111, 117-111, 116-112, that's a comprehensive points win here's a write up of the fight. "Like his previous championship fight with Tyson, Tucker was able to go the full twelve rounds with the much younger Lewis but was unable to put together much offense during the bout. Lewis was able to pick up a lopsided unanimous decision with scores of 118–111, 117–111 and 116–112. The Associated press scored it 117–110 for Lewis. So it's considered a lopsided victory with Tucker on average winning about 3 rounds and you call that competitive ? Tyson also beat Tucker by the scores of 119–111, 118–113, 116–112, again that's a comprehensive points win two judges only had Tucker winning a grand total of 3 rounds with their combined scorecards. The other 80s Heavyweights have more losses because they fought far more notable Heavyweights than Tucker did. Tucker only beat 1 ranked Heavyweight in the whole decade in the 80s. I think you're the only person i've ever seen that thinks that padding your record against complete nobodies is better than beating notable or ranked fighters because you have a prettier looking record against nobodies baffling logic.