In that build they went to dual 2080's so they could finally get to UHD 4K gaming.
Kudos on that first monitor (the only one I checked since it's a 1440p display which means you should be killing it on a single 2080. All the eye candy should work and hit 60+ FPS on everything.
To get anything more you'll have to hit the stores to see what you can in each monitor. There are reviews but you know your goals better than I do.