new one(it weighs about 7 lbs) - the new panel may cost a little more, but you'll save money on the install because your installer won't have to deal with trying to re-attach a used panel that has to be trimmed/added-to for a perfect fit. I'm not a body guy, but since this isn't a show-car I'd also get a price for having the dent banged-out & bondo'd & compare it against the price of removing old panel & re-welding new one.