tribe called quest
the roots
fugees
de la soul
cunninlynguists (newer but they are dope and better then alot of groups and being old doesnt make you the best)

honorable mention

public enemy
run DMC
NWA
bone thugs n harmony
pharcyde
furious 5
d.i.t.c

im sure there is some im forgeting......oh well

and i didnt add duos or eric b and rakim would be number one