there really is no comparison then. There can never be a "real" leader no matter how you do it. Homeruns will be tainted by the number of at bats, batting average in a reverse way is tainted. This guy hit 400 in 250 at bats where as the new guy hit 398 in 500 at bats.

It really is a shame that we can't truly track players throughout the years.
Even for homeruns the stadiums over the years have changed...I thought I hears somewhere that the fence in left feild I think in Yankee Stadium was pretty much made for Ruth, I could be wrong though.