I would recommend not getting triple monitors for gaming unless you are getting them for racing or flight simulators. They are generally not worth the money for what they offer. Basically it just looks cool, but for playing a multiplayer FPS, the benefits just aren't there.
For instance, the side screens that you would have in any FPS isn't actually a full screen. It is more like half a screen and then they take that image and stretch it to fit the display. So the visual fidelity on your peripheral vision, is not great. You also get this kind of fish bowl perspective, that doesn't feel quite right.
Then there is the performance impact. You are going to need some hefty cards to power these things at a playable framerate. And yes, I said cards. Plural.
But, if you are dead set on getting them. I would look for something like an Asus or BenQ 60hz display with the lowest response time as possible. 2ms is decent. I would say get 120 or 144hz display, but the likelihood that you will ever get a game to run at 120 fps or higher, is not very likely with the amount of GPU power required to push out the triple monitor resolution.