Taking into account you are comparing similar cards.
AMD - Runs hotter, uses more power, less expensive.
Nvidia - Runs cooler, less power, more expensive.
Nvidia has ShadowPlay, I'm not sure if AMD has responded to this yet.
AMD has Mantle, but it seems as if DirectX and OpenGL will be doing the same thing as Mantle.
GTX 780 Ti is currently the fastest single GPU in the world, unsure of how the Titan Black Edition will fare, but it'll likely be up there in performance.