Top 3 - 5 from the last few decades allowing a bit of overlap -
80's -
Eric B and Rakim, Kool G Rap, Public Enemy, Run - DMC, Big Daddy Kane.
90's -
Cypress Hill, Ice Cube, Brand Nubian, Ice T, BDP/KRS1.
2000's -
Fiddy, Juvenile, Dirt Nasty/Dyslexic Speedreaders, Ying Yang Twins.
2010's -
RA, The Rugged Man, Apathy/Demigods, Czarface, Vinny Paz, Sean P.
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There were guys that just barely didn't make the cut like Schoolly D, De La Soul, Jungle Brothers, Slick Rick, etc..... And there were others where maybe I went with one guy instead of the band, e.g. Ice Cube instead of NWA.