While re-listening to Bitches Brew tonight it occurred to me, there's never been anything that sounds quite like it since, and there never will be again.
The band[s] that jumps out at me when I think unique/original is anything that Les Claypool touches. It's never just him but he has a knack for finding people with unusual talent to make something different. Even when they are doing covers. For example the Frog Brigade doing Pink Floyd's Animals.
Tom Waits*
The Pixies*
Portishead*
Kruder & Dorfmeister the K&D Sessions
Massive Attack*
But maybe the most uniquely gifted musician on my list would be Richard David James.