I think we should recognize the fact that a QB is more likely to avoid a sack when he has better targets who recognize that they have to help him out. Also, having good OL who continue to block well even after a defender has gotten into the backfield helps a QB's ability to elude sacks.
I'm not saying I know who has the advantage in those aspects, but it's something to consider. In other words, I don't think these stats can show conclusively which QB's are better at avoiding sacks, when there are so many variables at play.