Both at their peaks (motivated, well trained, etc.), who wins?

Larry Holmes 210-215lb, 6'3, 81" reach
Joe Louis 196-207lb, 6'2, 76" reach.

Larry Holmes is one of the greatest heavyweights of all time, and a wonderful boxer. He possessed one of the best defences in heavyweight history and carried an awesome left jab. He also possessed great stamina and a cast iron chin. In his prime, very few would be able to defeat him.

Joe Louis would though. Holmes had a great defence, Louis had a better offence. He was the better boxer and the harder puncher, and also had more handspeed. Further, his jab was at Holmes' level and he had great stamina as well.

This fight would be very close all the way, but with Louis slowly taking Holmes apart. Holmes had a great chin sure, but he never faced anyone with the speed and accuracy of Louis (except maybe versus Mike Tyson). Louis would hurt Holmes and drive him to the ropes. They were both great counter-punchers, but with Louis' faster hands, I see him beating Holmes to the punch.

The first eight rounds or so would be even, then Louis would take over. I see Louis winning by late tko, or at least by decision. A great, hardfought fight!

Joe Louis by tko12.

holmes would outbox him to a ud.