You're completely discounting two important factors.
1) Career trends.
2) Park factors.
As it stands right now, Adrian Gonzales is a better hitter than Howard. He strikes out less, gets on base more and boasts similar power, which brings us to point number two:
Adrian Gonzales OPS+ 2007-2009: 143.
Ryan Howard OPS+ 2007-2009: 136.
When taking into account complete skillset and park factors, it seems clear that Gonzales is a superior all-around hitter than Howard, even though you can argue that Howard's a better "Power hitter".
And please look at both lineups before you even bring up the RBI argument.