Islam is the rare fighter that is both extremely deadly on his feet and on the ground. Both are world-class.
Khabib is the #1 GOAT wrestler in the history of the sport, and its tough to compare Islam's wrestling to Khabib's because Islam isn't grappling anywhere close to the amount Khabib did.
But Khabib's biggest weakness is his striking.... which... well... he wouldn't be winning any kickboxing competitions any time soon. It was piss-poor and its amazing how damn amazing his takedowns and grappling are to be so high up on the GOAT rankings, if only at 155.
Islam may have been in Khabib's shadow... at first, but since Khabib is no longer Islam's coach and Islam has been KOing so many opponents, that speaks volumes.