I can highly recommend the Samsung U32D970Q.
4K, 32", not overly excessively priced .. considering it's 4K and 32" and super high quality panel!
Calibrates as well as any other screen .. and 4K is just amazing.
it's hardware is 10bit capable which gives something like 99.something percent aRGB capable
Probably the handiest feature I've found on it so far is the ability to set two different colour spaces in a split screen mode.
colour spaces can be anything like sRGB, aRGB, or other obscure types like BT.709, EBU, DICOM, etc.
Obviously for photography oriented usage, splitting the screen between aRGB and sRGB can be useful.
Makes it easy to compare the same image set in two different colour spaces. The separator for each colour mode is vertical down the centre of the screen only.
I can line up (for example) Capture NX-D to use the split screen/compare view mode so that each image lines up along the central split line.
The only problem with this feature is the convoluted OSD menu system needed to access it(requires about 10 button presses to activate it). Would have been better in the easier to access Colour mode section of the OSD, where two or three button presses could have turned it on/off.