The ROG is what I'd get. It is 1440p, 144hz with G-sync. For gaming, that will give you the smooth experience.
The PB278Q is better for desktop use.
but will my sli 780s be able to go above 60fps even?
You aren't serious, are you?
Of course it can, so can a single 770, or 760, but you might not be able to always play at completely maxed out settings. Your biggest obstacle will be your CPU, which you did not list. Some games will be CPU bound, not letting you to always be above 60.