my monitor advice may not always be feasible but still here goes:
don't buy a monitor unless you have actually laid eyes on it. you will be staring at this thing for a long time, your eyes are experts in the matter consult them.
go to a store and actually take a peek.
personally I like the AOC's curve, but I prefer the looks of the DELL.
you will also need to make sure your GPU can handle the extra refresh rate