For similar use although 80% of my time is illustration now, we’ve bought the most recent 27″ thunderbolt displays, can’t fault them but they are expensive RRP circa £750, I think.
Also used the most recent Samsung (can check model number on Monday) connected via HDMI but it’s not a patch on the apple, but then it was also £300.
I would also steer clear of retina type screens to retouch on as at 100% view the details are too small to work on and it’s difficult to judge image sharpness, you have to go to 200% on a higher dot pitch screen to get the same size and then it’s interpolating not pixel per pixel (screen to print)
This is a pain in the arse^ only downside