ME!!!!
No really Steve Vai, Mike Keneally, and Frank Zappa. I base this on ability. Zappa wasn't the most fluid but her came up with some amazing stuff. He was smart enough to realize that he couldn't play the stuff he wrote so he hired people who could like Keneally, Vai, Adrian Belew, Ike Willis and the list goes on.
Download a song called Beautiful by Mike Keneally if you don't believe me. Your ears will love you forever for it. He plays and sings that shit at the same time. He's also the musical director for the Paul Green School of Rock and does one of the voices on Metalacolypse.