It's not a greatest careers list. So if you saw Brady and Manning and you think you know which one was better however you determine that, I don't think both should be on such a list. If you're not sure, definitely include both.
There's no Lawrence Taylor because White doing it as a true down Lineman in that era is more impressive to me. There's no Calvin Johnson because Moss was better. There's no Ray Lewis because his teammate is the very first name that comes to my mind as the perfect player. Reed also keeps Ronnie Lott and Deion off of the list and I think those last 3 names are perfectly defensible in a top 10 all time list. 2 of them would probably make my top 10.
But I did forget Anthony Munoz. Good luck really evaluating an OL from that far back, but I would believe it with him.