I should probably go back and watch the movie (or at least listen their respective Woodstock collections (I know Hendrix and Santana each have one, though I'm not sure about Cocker)) before answering.

But based purely on memory, I'm going with Santana, if only for the reason that with access to all three of those dude's Woodstock performances over the years, the only one I've gone back to over and over again is Santana. Specifically, "Soul Sacrifice" from that show. It was phenomenal.

There's an awesome quality version of that peformance available on Vimeo, but for some reason it won't embed here. So I'll give the link, and then below that I'll insert a crappier quality version of the same thing from YouTube:

https://vimeo.com/63053717