The best match-up if you're a fan of Conor's, or even if you're a hater is Frankie Edgar. If you're a fan, then you have to believe that Conor is every bit as talented as you thought he was, and if he lands even one of those lefts he landed against Diaz, Edgar is either out or on his way to being finished. If you're a hater, then Frankie has all of the tools to beat McGregor, as long as he can avoid Conor's power early in the fight. I also am not of the belief that Conor has zero BJJ, but I don't think that it was high level enough to hang with high level blackbelt like Nate Diaz.
Aldo's ability to absorb shots was being questioned even before his fight with McGregor, and 6 or 7 months is not enough time to recover from having your lights shut off. It's would be ill advised for Aldo to fight at UFC 200, to say the least.