Obviously, Dwight. And why...
Dwight could get 20 rpg if he stopped help defending and protecting the rim, and just focused on getting good position for rebounds.
Love probably gets a chance at 5 extra close rebounds each game because people go at him. And he's always in position because he doesn't block shots and doesn't help defend that much.
Love's shooting range is nice. But if I have to choose between 20 points from a slowish PF who can shoot, and 20 points from super athletic center who can both play quick game and who now has go to post moves... and who needs to be double teamed or at least draws a help defender very often.... I take the center. PF is easier to replace, and shooting is easier to replace.
The only things that Love has over Dwight are passing (esp outlets) clutch offense (not that Love is great but Dwight gets scared to be fouled). But you can live with that.
And obviously defense is incomparable. That would be like comparing DeMar's and Pippen's defense.