Jake LaMotta was an animal in the ring and couldn't turn it off when he stepped out. Still see plenty of athletes like that today.
It's hard to compare across genres, but Hoosiers is a clear second, for me - also great acting and direction. Then you have Rocky, Rudy, Cinderella Man, and Miracle, which are the best underdog stories after Hoosiers. The Greatest Game Ever Played is a good one in that vein as well. Seabiscuit, The Natural, and Field of Dreams are great because they tap into the spirit and magic of sports. Bull Durham, Major League, and The Sandlot are the best sports comedies.