i dont know... their rhyme skills are apples and oranges if you ask me. very different content-wise, and style........ raekwon and andre 3000 are both lyrically on par with just about anyone in my book. i thought about the wu as well but they havent had the long-termimpact on radio and mtv that outkast has had.... they are just more consistantly getting radio hits that are solid songs, usually having a new twist of production or a different flow.... (in my opinion)
plus, even though i dont really like the south, FORGET master p, FORGET cash money, outkast has by far been its best represntative of the south in hip hop, and they are highly regarded and respected by the current crop of artists from the south.
then again its hard to measure the impact that the wu has had on the underground scene, because arious elements of their sound is everywhere... damn near every backpacker here in california has a wu sticker on their bag (i confess i was one at one time!) and these guys regard wu tang as their patron saints, much the same as the roots.