we could make a list.
You could also throw in Nore, Mos Def, Pun, Kurupt, and if you believe urban legends, all of Wu Tang.
he was literally battling now-legendary MC’s in their prime… during arguably the greatest years of the culture… and coming out with the most memorable verses of them all.
Anyone calling Bis underrated obviously was not part of that era.
Even Redman got dusted on "Beast from the East" by Bis and had Prodigy all
Big Pun had to rethink his verses, and NORE know already he gonna get killed, so he was rhyming for the hell of it 
Canibus was a whole force of nature. Savage intellect and fierce determination to roast MCs on some Godbody shyt.