It all depends on how you would define the word best,action,skills,knockdowns,come from behind,a masterclass,brutal KO finish,ring generalship,excitement,etc etc .
Usyk vs Fury, two elite, brilliant, undefeated fighters going at it for the best of the generation. If the referee breaks up any holding, and as long as the judges are fair so there's no bitter after taste- we could see something special with different ebbs and flows from two not only fantastic fighters with high boxing IQ's , but two very mentally tough fighters who don't know how to lose.
Agree w/ some above - there's no criteria suggested or given as what makes "best." My top 2 are: Tyson Fury vs. Oleksandr Usyk, Filip Hrgovic vs. Daniel Dubois Next is Andy Ruiz vs. Jarrell Miller for the Obeseweight title They could promote it as Rolls of Thunder ! Zhilei Zhang vs. Deontay Wilder I'm not high on although there will likely be a T/KO. Among the rest there s/be one good scrap.
Fury-Usyk of course. The two most talented fighters who appear to be in great shape. I expect this to be a high skill matchup. Fury could make it ugly but the fact that he appears trimmed down makes me think he will try and out box Usyk. I, like many, have been looking forward to this for the past two years and finally, it appears Fury will show up.
If you mean just looking at both men as just boxers then probably dubois v hrgovic but in terms of pure intrigue from start to finish watching intensely then has to be usyk v fury