Can't really compare the same cooler on a card that uses entirely different processor architecture and board design.
All in all, they are both great coolers, but I think Sapphire wins this one by a thread. Whatever you heard about the Vapor-X was probably just caused by a damaged or malfunctional product. It happens to pretty much every manufacturer out there from time to time, but all I've heard from Sapphire is good.
And like you said it looks much better. I think Gigabyte design looks rather cheap and feels pretty flimsy overall.