Yes, but there’s still subjectivity that can’t be avoided—so I wouldn’t say that selecting a fighter based on criteria is even objective.
I’ll give some examples.
Ranked wins is something that most fans agree is a good metric. From about 2014 on, the UFC has issued rankings. So if Izzy, or Stipe, or Usman, beats a guy that the UFC has seen fit to rank in the top 10 of their org, it’s a ranked win. But if you try and compare them to Anderson, Fedor, or GSP, you have to go back to a time when the MMA media issued the rankings, and it was across all promotions. They listed the best 10 WWs (or HWs, or whatever) in the world—not 10 best in the org. And sometimes one outlet had a fighter ranked and another didn’t. So then what?
Title defenses can be an issue too. Which titles do we care about? UFC, Strikeforce, PRIDE? What if someone is WEC or Elite XC champ? What about Fedor and Aoiki’s WAMMA belts? Should we count them but weight them differently? And if so, why?
And so on, and so forth…