Dispatch.
Hands down.
I saw them live once, a 3 piece jam band that was relatively big (are they still big) because of myspace and giving away their music. You can not have a 3 piece jam band when no one can hold their own on the instruments, flubbed notes, poor singing/harmonizing/just dying songs had many who were not there for the show openly claiming "worst ever".
Who, who is putting down Led Zepplin, the Dead, or Rush or the others actually saw them live in their heyday? Some bands I do not like any of their studio work (or very little), but live they can really put it on, entertain a crowd, and hook even the casual listener in. I was talking to a friend who was into the first punk explosion in the UK (saw the Sex Pistols first time round). Hated Led Zep but a friend begged him to go to the show. In the end he was won over, not a fan but respected them and said it was a great show.
So again, dispatch followed closely by Evanescence and Book of Love. This is based on touring bands headlining gigs.