I agree they would probably be tiered the same if I decided to ever do one of those Tier memes. They're both people you'd want for your company as Edge was a work horse and Big Show was the ultimate company guy. I've been watching all of the AE on WWE Network and Big Show had so many ups and downs even in his first year. I'll be honest as well, I really enjoyed the Big Show breaking into Hollywood gimmick.
Reason I'd say Big Show was a bigger draw is simply due to his size. His matches against Akebono ad Mayweather were perfect proof of this. He has a unique presence to him.
Edge for 5 star matches and Big Show for the spectacle.