Pej, I confess that I'm thinking in terms of the modern game. It's hard to judge Halas against the other names on the list simply because of the sea-change of difference in the game from Halas' era, when (for most of his championships) there were 10 teams or fewer in existence.
It's similar to judging the greatest football player - it's tough, after all, to compare a guy like Slingin' Sam Baugh to Sweetness.