Per myself, since i've never seen the Butkus, Nitske, Huffs and even Lilly's actually play the game up front before my very eyes, ..i have only to go off hear-say, and You Tube and NFL film highlights and their respective reputations .
And these are only the guys aforementioned in your post. Ditto with the Jim Brown, OJ Simpson, Gale Sayers, Deacon Jones, etc, ) .and only limited resources
Those aforementioned guys were way before my time, and I myself by most accounts, like and prefer to compare and rank according to those players I've seen personally play the game
at some earlier points. .
Now oh thank the heavens for the advancement of YouTube whereas nowadays we can view back more highlight and " occasional " full reel game time,.. but that's still rare games, and not
a series of games and seasons, as we have available for the Emmitts, Zekes, Walkers, etc.