I'll just throw some names out there.
Big l, rakim, krs-one (he's been rapping since 85 or so with BDP and he's still at it), nas, immortal technique (not only does he have amazing lyrics but he is also one of the most recognized and accomplished freestylers out there), jay-z (yes. he is a biter. alot of his lyrics are borrowed/stolen from artists like biggie. But his flow is oh so smooth), afrika bambaata (one of the legends that started hip hop), zion i, too short, snoop, eazy-e/nwa (I'd accredit them to being the ones responsible for bringing the gangster image to rap)