I use a 32" LG 4k VA monitor. I bought it last cyber Monday for $350 at newegg.
With a 980 ti I played Skyrim SE at 4k with Reshade. Frame rate is in the 40s. Very playable.
If like me you only do 60fps gaming go 4k 32".
All the 4k panels I have owned were excellent at 1440 as well.
The downside to 4k gaming is that it takes a lot of GPU power. I now use a GTX 1080 ti.
The other negative is that they are terrible at 1080 resolution. At least the ones I have owned(Samsung TN 28", ASUS TN 28" & LG VA 32").
For the type of games I play I prefer VA monitors. Although the next monitor I will buy will be a 3840 x 1600 IPS widescreen monitor if I get a deal next cyber Monday.