This is the most absurd thread I've seen in a long time. So many arguments, so few numbers provided to back it up.
Of course we should be using numbers, and there are numbers we could agree to use that have been painstakingly crafted to provide a comprehensive view of a player's seasons. Win Shares, VORP, WARP1, 2 or 3, OPS+, are a few examples. Or we could look at counting stats because, as Kilo correctly pointed out, it is worth looking at counting stats because the better hitter is the one who actually plays consistently for his team.
The list of career OPS+ RHHs better than Manny is very similar to Crespo's list... that seems like a decent start. I don't know about McGwire, but his numbers were really solid despite his drawbacks. I think it is also important to include switch hitters. Mickey Mantle hit RH thousands of times and put up good numbers there. Yes, he was a switch hitter, but he could hit RH pretty damn well.