The only player I watched who played as hard as Russell was Dave Cowens. Cowens was a fraction of the athlete Russ was, but, nobody wanted to play against him either. Part of "defense" is intimidation and both these guys had it in their game.
As a homer? Big deal who else is on the list. Cowens would injure himself and his opponent over a loose ball in a meaningless game. Russell and Red invented NBA defense. Get off the stat train and watch the games. KG is in the discussion too, obviously.