Women's Strawweight - Joanna Jedrzejczyk
This is tough Zhang and Joanna are the two to consider and both lose to Rose Namajunas twice...but I'm not sure she really could be considered as the best ever of the division. She just had too many losses where she didn't look like a goat in them. She can never be counted out but IMO it comes down to Weili and Joanna. Joanna was truly epic as the division was launching. Six title fight victories over three years and looking unbeatable going it...she did lose to Weili twice, but it was after her slide and past her peak. Weili is definitely able to get there possibly even very very soon.
Women's Flyweight - Valentina Shevchenko
Young division, not sure there is much debate or discussion here.
Women's Bantamweight & Featherweight - Amanda Nunes
Again, not sure there is much debate or discussion here.
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Men's Flyweight - Demetrious Johnson
Pantoja really has a great chance to top him but until then I have to keep giving it to DJ. He was as dominant, possibly even more dominant. He was able to do things nobody ever saw guys do before. Sadly I don't think DJ has any reason or desire to accept Pantoja's call out so this may be a dream fight left for the video games.
Men's Bantamweight - Dominick Cruz
As much it pains me to give Cruz his flowers it has to be him. Dillashaw was probably the biggest buzzsaw I saw with so many incredible angles and abilities nobody else could match, but Cruz beat him head-to-head during his prime and looked good doing it. Sadly the injuries took a lot of fights away from him.
Men's Featherweight - Alexander Volkanovski
Yea, everybody is saying Ilia Topuria already and he's had absolutely the most impressive back-to-back results, KOing both Max and Alex, but Volk was so dominant and help his own against the a bigger guy in a weight class up in a 1-2 p4p fight. I'd put Volk up against Prime Aldo and would expect Volk to win.
Men's Lightweight - Khabib Nurmagomedov
I really don't know who or what strategy could have beaten Khabib. I wasn't a big fan of his but he was as much or more of a mauler as anybody ever.
Men's Welterweight - Georges St-Pierre
Yes, I was the one who posted about Robbie Lawler not even getting a mention. Purely needing a guy in a bar fight behind you...I'm taking Ruthless all day but GSP definitely deserved the GOAT status of the division and hasn't been topped yet.
Men's Middleweight - Israel Adesanya
It's very easy to just say Anderson but this would be a true all-time dream fight (prime vs. prime -- yes I know they fought but it was well beyond prime Spider). Izzy lived up to the Stylebender nickname. Sure, he's lost three of his last four but during his peak he was as untouchable as you could get. Before losing to Pereira he was unbeaten outside his attempt to go up to light heavyweight against Blachowicz but after losing that he came back and took out three top tier guys. He also avenged his loss to Pereira with an incredible KO win. Head-to-head in their primes I honestly think I'd pick Izzy over Anderson.
Men's Light Heavyweight - Jon Jones
No doubt for me. He was the most incredible guy in the rich division's history. He beat every great of his era and was barely even challenged.
Men's Heavyweight - Bas Rutten
IDK man...it's so difficult. So many open weight fights early on...so many different rule sets. Fedor gets all of the love but he got KO'd by Hedo...tapped by Werdum (dude needs way more love), topped by Bigfoot...and then KO's but Mitrione and Bader twice...it's just too much against guys who were not really heavyweights or not really top-tier guys.
Bas won everywhere and figured out how to become a complete mixed martial artist just by watching film with no real training...he figured out everybody except Ken Shamrock, who left to go to WWE before he got another crack at him.