Very tough call, but I went for Neil Young.
Dylan at his best is pretty much unbeatable, but between 'Desire' and 'Love and Theft' there were 2 decades of pretty much bugger all.
Neil Young is also pretty erratic, but he's been knocking out good and occasionally excellent albums since the late 60s and there's clearly plenty of life in him yet.
Ditto live performance - Neil Young is almost always electrifying on stage, especially with Crazy Horse, while Dylan is patchy at best. having said that, I recall a London gig where, after over an hour of scratching abstractedly at his guitar and casually massacring his back catalogue, he played an amazing Simple Twist of Fate and made strong men weep, and the remainder of his set was almost as good. I was glad I didn't leave after the first hour.