The display market is on fire right now. It looks like there are a few competing standards and the prices will likely be much lower come Nov/Dec. I'm waiting. Here are what appear to be the most popular display groupings.
Single GPU
27" 16:9 75+Hz IPS Free/G Sync 8bit+FRC/10bit 2560x1440 4-6ms 300+(nits/cd/m2)
High end/Dual GPU
34" 21:9 75+Hz IPS Free/G Sync 8bit+FRC/10bit 3440x1440 4-6ms 300+(nits/cd/m2)
This 4k pocket appears to be mostly TN
28/32" 16:9 75+Hz TN/IPS Free/G Sync 8bit+FRC/10bit 3840x2160 1-6ms 300+(nits/cd/m2)
Full List