I just got a screen when I switched from my iMac, so some of this is still somewhat fresh in my memory… You will find that Mac screens are hard to beat as far as quality is concerned. For accurate colours you would be looking for a monitor with In-Plane Switching (IPS) or equivalent technology such as PLS. OLED is great, but they tend to be a bit expensive still. 10 bit is probably not necessary.
As far as size goes you probably want 21-30 inch I assume. If you are doing video you are probably looking for a 4k / UHD monitor? I use a 27″ UHD (3840×2160) and find I wouldn’t want to go smaller, though larger gets more expensive for the same quality. A 30″ with the same resolution would probably be ideal for me.