I've seen people perform with backing tracks, and I couldn't wait till they stopped... it was awful.

But I've also seen people perform with trax and they blew me away, they dominated the stage.

Same goes for full bands, solo acts, people playing covers, people playing original music... even DJs... there are interesting examples and boring examples of each.

my preference, since that's what we're mostly dealing in, is to be entertained , and that involves more than proficiency with an instrument or quality of background music. It involves stage presence, audience savvy, personality, wit, and the ability to "ramp it up" so the presentation stays interesting the whole time