…has got to be the sure shot. One of my favorite aspects was the way that they fused jazz and hip hop in such creative ways; but what I really loved was the distinct soundscape provided by DJ Premier. In fact, it seemed like he could create (arguably) some of the best beats for any rapper he blessed to rhyme over, while still giving Gangstarr its own unique sonic landscape. 
And Guru? His rhymes were jazz verbalized, and his position as one of the greats is unquestioned.