JJ technically is by far the best in men's or women's, wonderboy, barbosa, Jon Jones, and DJ round out my top 5
Definitely don't agree that Joanna is better than the men. The level of competition she's up against is far, far too low to make a claim like that. Wonderboy got dropped multiple times by Woodley and once by Ellenberger, the only really good striker he's beaten is Rory who's a good stylistic matchup for him. As I said in another post, I don't think he can be ranked in the top 5 until he beats someone like Lawler, Cerrone, Masvidal or dos Anjos. Jones and MM are great on the feet, but why rank them over guys like Aldo, McGregor, Holloway, Garbrandt and Dillashaw?
Aldo was undefeated for a decade and outstruck everyone who isn't Holloway or McGregor, though he did outstrike Holloway for the first round. His leg kicks are crippling, his jab is fantastic, he can knock people down with either hand and his knees are vicious. In addition, he has some of the best footwork in MMA history and arguably the best TDD of any striker ever. Notable wins include Edgar twice, Mendes twice, Lamas, KZ, Hominick, Florian, Brown and Faber.
McGregor is probably unbeatable at featherweight and ran straight through that division, his only setback in the UFC was a loss to Diaz after gassing out but he avenged that loss then embarrassed Alvarez in a way that's never been done before. His counter punching is pinpoint, his combinations are deadly, his head movement and distance management are top tier and he has a versatile kicking game on top of it. His main weakness is cardio. Notable wins include an early one over Holloway, Poirier, Aldo, Diaz, Mendes and Alvarez.
Holloway's last loss was to McGregor, and since then he followed in McGregor's footsteps by essentially cleaning out the division with the exceptions of Mendes and Edgar, who's up next. He's the best bodysnatcher in MMA, measures and manages distance extremely well with his jab, has a varied attack with a ton of volume and is one of the best, most active feinters in MMA. Notable wins include Cub, Stephens, Lamas, Pettis and Aldo.
Garbrandt is undefeated with 9 of his 11 wins by knockout, he derailed the Thomas Almeida hype train, steamrolled Mizugaki then styled on the Bantamweight GOAT and knocked him down multiple times. Many even think he could have finished Cruz if he did less dancing. He has insane power and can put guys out in the first minute, but if he needs to fight a more technical fight he can hang back and show off some of the slickest defense around. Notable wins include Almeida, Mizugaki and Cruz.
Since working with Ludwig, Dillashaw turned into a killer. He won the Bantamweight title with his striking and lost it controversially to Cruz. He's known for being the most prolific stance switcher in MMA, supplementing that with great head movement, a nice jab and a strong kicking game, plus volume for days and crazy combinations and exchanges in the pocket. Notable wins include Barao twice, Assuncao and Lineker.
I'll give you Barboza, I included him in my original list too, but even he's been outstruck by Varner, Cerrone and Johnson so it's hard to put him above the guys I just listed.
I could see replacing Garbrandt and Dillashaw with Jones and MM, Garbrandt because he's had so few fights and Dillashaw because he did lose to Cruz, got TKOd by Dodson, struggled a bit with Soto and also could use more big name wins.