They're about the same for performance and power consumption as they are the same card. I prefer the MSI twin frozr design, it is quietest coolers out there but it is about an inch longer than the Nitro but cooling performance will be nearly the same give or take a couple of degrees in favor of the MSI card in some cases.
I've heard some people have trouble OCing the Sapphire card due to voltage limitations, but have not looked into it yet. At the end of the day you can't go wrong with either, both great coolers from great companies.