Of the three I mentioned, Jack has been the greatest legitimate musical influence for me. His background is known to relatively few, (IMHO) having been eclipsed by the Cream phenomenon. My teacher tells an interesting story about Jack's influence: Steve Swallow attended a Cream gig backstage and decided to switch exclusively to bass guitar. I tend toward skepticism about dramatic conversions like that, but my teacher maintains Swallow told him that personally when he studied with Swallow.