Holmes, and pretty easily. Late stoppage if it's 15-rounds fight. But I would clearly favor Holmes against guys like Lennox and Vitali as well, he was incredible fighter in his prime
Possibly the best jab a heavy has ever displayed vs a guy that moves his head as though his neck is in a brace? Holmes all day.
Lewis didn't beat 36 y.o. inactive, 3-years winless Ray Mercer, while 42 y.o. Holmes completely schooled prime, active, unbeaten version of Mercer. Holmes was far better boxer than Lewis - more skilled, had far better chin, stamina, work rate. Lewis only had size and power over him, but that won't be enough to win, especially considering the fact that Lewis always struggled badly against jabbers, and Holmes was the best HW jabber of all time. Holmes would clearly beat Lewis and stop him late.
Lewis went life a death with Mercer who a 42 year old Holmes schooled with ease. If you think Lewis beats Holmes easy then obviously you've never seen a Holmes fight, Lewis got out jabbed by the likes of Mercer. Holmes would give him serious issues with his ATG jab.