Based on Rapping ability it would be something like
MF DOOM > Aesop Rock > RZA > El-P > Kanye West
Of the group, DOOM's got the most consistently tight flow with the best wordplay, followed quite closely by Aesop Rock (a few inconsistencies here and there). RZA flow is phenomenal at it's best and great at it's worst, while El-P suffers from IDK what when it comes to his flow. Lastly, Kanye is only on this list because, aside from his highly derivative work, he's a solid producer that rapped once or twice.
in terms of Production it's gotta be
RZA >>> El-P > MF DOOM > Aesop Rock > Kanye
RZA is KING when it comes to production. Hands down untouchable. He's often imitated (especially by Kanye) but is never EVER duplicated. Look at the work he's done on 36 Chambers in his basement using his TV for monitors. Look at the Ghost Dog, Afro Samurai, and Kill Bill soundtracks. Look at how his beats are ALWAYS distinct.
El-P, while his execution is usually spot on, isn't quite as spot on as RZA.
MF DOOM is creative as all everything, thereby earning him a spot ahead of Aesop Rock and Kanye.
Aesop Rock is nothing special when it comes to production, but at least his work carries his signature, which is more than I can say for Kanye.
Kanye is highly derivative and substance-free. He produces bland beats for the masses where the others excel and have flavor.