Ali. It'd be the Buster fight all over again, albeit Mike wasn't at his prime then.
Ali would dance, dance, and his awesome jab would keep Mike off him. Buster exposed Mike as having poor against the jab. He could weave, but he didn't move his feet much when he weaved, and the size differential would set him up for an anchor punch from Ali.
The vast majority of Tyson's wins came against big brawling heavyweights with little skill, or guys who were already defeated before they stepped in the ring (Sphinx). Ali fought against 3 of the top 10 heavyweights of all time. Tyson could get lucky with one shot of course, but Ali maybe had the best chin of all time. It'd take more then one shot.