The trouble here is they fought in the same era, but didn't peak at the same time.
Tyson won a Title in 1986, and his peak was 1988, particularly against the undefeated lineal Champ Michael Spinks.
Holyfield, though the Cruiserweight Champ, only went to Heavyweight in mid-1988.

In the 1989 Bruno fight, I think Tyson was already showing a few problems, maybe not showing as much focus and dedication, maybe not training as hard. He won the fight, but he wasn't as awesome.

In 1989, Holyfield took out a good contender in Alex Stewart as he made his way up the ladder and developed into a better fighter.

In early 1990, Tyson was KO'd by Douglas.
In late 1990, Holyfield KO'd Douglas.

The big showdown was scheduled for Nov 8, 1991.
There were posters hyping it in the magazines, but Tyson got arrested for rape and later went to jail instead.

Tyson had been back on-track after the Douglas loss though, at least in the ring.
Leading up to Nov 1991, Tyson had KO'd Tillman, Alex Stewart, and did the 2 fights with Razor Ruddock. Fighters were no longer scared stiff of him because they had seen him getting knocked out, but it was clear he was still an elite fighter.
In contrast to Tyson's 4 fights resulting in 3 KOs, Holyfield had only fought once, and it was a very tough decision win over 42 year old Big George Foreman.

After the Holyfield/Tyson Nov 8, 1991 fight was scrapped, the promoter decided to try to make a little money anyway, so Holy's defense was rescheduled for 15 days later with a last-minute opponent. Old trial horse, Smokin' Bert Cooper, who fought a lot like Mike Tyson, took the fight though he was just coming off a cocaine-fueled, month-long bender, and he still almost knocked over Holyfield.

I think at that period in Nov 1991, if the fight had come off, I think Tyson would've been too much for Holyfield. And that's even with Holyfield's "supplements" that built his 188 lb body up to 208
.