I use 3 Qnix QX2710 1440P monitors. I just recently went from and AMD setup with eyefinity, to NVidia with surround in the last week. The NVidia surround takes my vote. Maybe a year ago it may have been different but NVidia seems to have everything AMD does now and it works better.
Opened windows remember their last known locations. With AMD every time I would open something it would show up on a different screen, and usually open up across all three screens maximized. Hydravision worked but not perfect in my experience. Had to hold down a special key at the same time of pushing the maximize button. With surround when I maximize something, it maximizes to the screen it is currently on, not across all three. YouTube videos did not work full screen with AMD under Chrome, now they do.
The biggest thing i did not like with eyefinity was the fact that the outside screen were magnified and blurred to the point of just looking horrible, especially when looking close up. With surround the outside screens looks just like the center screen.
I took a picture of this one instance, that right screen does not look so good.
As for a single 1440 monitor it is awesome. I would have never spent $600+ dollars for one but I came across these Korean displays with Samsung PLS panels inside of them. They look great and many of them will run at 96-120Hz as well. At least with the DVI input models only. I have the ones with multiple inputs. They were $359 each. I found the ones with just a DVI input for as little as $289 but did not last very long. Typically there were $329.
I bought two at first and added a third a couple of weeks later. The first 2 arrived from Korea to me in the US overnight. and the third one I ordered took 2 days!