Conor always, Khabib is a max 700k guy on his own (and that's being generous), he got a serious boost from the 229 fight against Conor, before that he was doing 350k buys in title fights.
Conor can fight literally anyone on the roster and do an easy 1.2mil buys right now bare minimum.
Even at Khabibs peak he wasn't touching 700k unless Conor was involved. I think his last fight against Gaethje was in the 650k range. They are not comparable on the commercial side, Khabib was largely unknown to the general public before the Conor fight, his fight against #9 ranked real estate agent Iaquinta did around 350k buys. He literally went from a guy most people didn't care to watch, to a household name amongst the casual fanbase just because of the Conor fight. Conor could've fought anyone after his 4mil buy event versus Mayweather, and that other opponent would've become a household name.
The A side is the guy who can make money and sell events anywhere he goes, Conor can fight Bobby Green and it'd be the biggest MMA event in years.