I can tolerate Buckethead. He's done some good stuff, but after so long, you just get bored of it. I almost never listen to him anymore and if I do listen to him, there's only a couple of songs that I can listen to.
Never heard of this John 5 guy, but my guess is that I won't like him.
Both suck balls IMO. Im a musician, a bassist, and i find guitar rock for the most part pretty unlistenable. Its music just for guitar players to show off to other guitar players. That being said, Buckethead is more technically accomplished than John 5.