I feel like Holmes - Foreman would've been the most significant fight, but Lewis - Bowe would've been the best.
Lennox-Bowe - it was the most appealing @ the time, & continues to be the most appealing in retrospect IMO.
Holmes-Foreman didnt quite line-up time wise in the 70's and I didn't care as much about two old men slugging it out. Fantasy-wise that would be my fave. But in reality the Lewis-Bowe fight not happening was a bigger shame.
I just assumed the OP was referring to the old man versions of both, since Foreman had already retired before Holmes emerged as a star.
There isn't a realistic heavyweight fight that I wanted to see more than Lewis vs Bowe. It would have answered any questions we have about Bowe's quality.
Lennox Lewis v Riddick Bowe by some distance. That fight was meant to define the modern era of boxing with these super big and talented guys. Both were genuinely top 5 in a prime for prime H2H sense. Still lost for words the fight didn't happen in 1993.
Not gonna belabor the point but the Holmes who was fighting Roy Williams was already better than the John Dino Denis, Scott Ledoux and Pedro Agosto who Foreman was facing around the same time.
On paper Foreman V Holmes would be one of the best fights ever. But I feel if they fought in the late seventies and had Foreman beat Young instead of losing then taking a sabbatical and was still in his prime, I think Larry's jab and ring IQ may have been too much for Foreman then. I think Larry was pretty bad for George stylistically. Can see arguments of George winning this but I think style wise Larry would win this.