I gotta say when I think Athletic ability.
Foreman is not one that springs to mind.
Sure somewhere in the list but top 10 I wouldn't list them there.

Ali, RJJ, SSM, SRR, SRL, PBF, Tyson, Meldrick, Duran, Hearns, Wilfredo Gomez, Cory Spinks, Zab Judah.
And someone whom I think get's overlooked is Tszyu if you've seen him train you'll see how athletically gifted he is his workout routine is insane.

From this new generation I would say Khan.