Movies made by Robert De Niro in the late 1970s include Godfather II, Taxi Driver, Deer Hunter, and Raging Bull. That's a pretty good stretch.
From 1982-1986, Gerard Depardieu starred in (amongst much else -- he pretty much carried the French film industry on his broad back during the 1980s), Return of Martin Guerre, Danton, and Jean de Florette.
From 2000-2005, Russell Crowe starred in Gladiator, A Beautiful Mind, Master and Commander, and Cinderella Man.
These kind of halcyon periods for leading men (when they're both at the top of their acting and their movie star games) never last terribly long. Perhaps the star gets tired, or audiences just get tired of him. By the time you get around to realizing so-and-so is the top dog, he's probably over the hill.
Anyway, that's just an intro for my new movie review in Taki's Magazine, in which I give my guess as to who is the best right now.