jus allah
canibus
Kool G Rap(dont know how he couldn't be on any of the lists)
krs-1
eminem(i hate him, but can't deny skills)
kurupt
Rakim
Killah Priest
LL Cool J (just cause of his canibus diss)
Common Sense
Tech N9ne
method man
Aesop Rock
Mos Def
Talib Kweli
Ikon
Supernatural
El-P
Mr.Liff
SplitSouL

thats all the best rappers i can think of at the moment