I think the Lightning has an ACX style cooler so that one gets my vote.
The Lightning is MSI. It's not going to have an ACX cooler. It'll likely have a better PCB though. $500 is too much for a 780 at this point in time, IMO. The Asus DCII is a good suggestion.
Derp, thats why I said ACX style. Would it better to say ACXesque or the cooler formerly known as ACX? The point is it doesnt have the slot cooler which is less potent given the open cooler is with adequate case airflow.