The increase in power due to steroids is one thing, but Sosa is one of the only players that dramatically increased his walk rate in his late 20s, early 30s.
And Brett, Frank Thomas was not a better homerun hitter than Sosa. I will give you that Thomas was a way better pure hitter than Sosa, but Thomas never hit more than 43 homeruns in a season. Thomas also never lead the league in homeruns at any point. Thomas was a great hitter, and I would probably take Thomas over Sosa if I had to pick between the two. Sosa cheated to accomplish being better at hitting homeruns, but he was better at hitting homeruns than Thomas.