You say you are going to do graphics work and color production is important? TN/VA is out of the question which moves onto 2x 1080p vs 1x 1440p i assume u meant? You didn't state what screen size you want. Though I ask if have you ever seen a 1440p monitor? If not, it is a considerable jump from 1080p... I personally recommend 1x 27 inch 1440p (Korean) monitor for you as you can use your current monitor as a secondary.
Though the next question is PLS vs IPS which I still don't know the answer to.