Regardless of his past indiscretions with PEDs.
Out of all the GOATs, I believe Jon Jones has the best resumé. He fought the toughest competition. More than Fedor, GSP, Anderson Silva, Mighty Mouse, Aldo or Khabib.
Also he can even cement even more if he becomes HW champion.
And this is coming from a huge Fedor fan.
Jon Jones notable wins:
Stephan Bonnar
Brandon Vera
Vladimir Matyushenko
Ryan Bader
Shogun
Rampage Jackson
Lyoto Machida
Rashad Evans
Vitor Belfort
Chael Sonnen
Alexander Gustafsson - 2x
Glover Teixeira
Daniel Cormier
Ovince Saint Preux
Anthony Smith
Thiago Santos
Dominick Reyes
Edit: Just to clarify this is not about GOAT talk or if he took PEDs. It's talking about who fought the toughest competition in their careers.
If it's about who's the GOAT, I'd choose Fedor.