I have friend who is a professional photographer she uses a Dell UP321K bear in mind that if it is not for professional use, then a professional unit is a waste of money and good home monitor would suffice
currently 4k is all the rage, 99% of people cannot see the 4k resolution.
Manufactures are producing higher and higher resolution because they can, this is great for sales staff, although in reality we can't see it.
With any monitor it is worth having it professionally calibrated