Apart from the newly-released AMD Fury X, nVidia has definitely had the edge over ATi/AMD. With the Fury X, AMD has the technological advantage (better/newer underlying tech) but nVidia has them in check with their latest flagship offerings due to sheer brute force and better engineering. For a more bang-for-your-buck, the older AMD cards (such as the 290x) are great.
Nvidia fan myself. Better support. Since AMD took over our Canadian ATI their support is not nearly so good as it used to be so I switched long ago.
But really it all depends on your personal choice. Just do some online research for whatever card(s) you pick.
Actually it's rare that anyone should ever need support for a graphics card anyway.