I have one big 4K 43" monitor at 60hz for most desktop work, sims and non-shooter games. Where the second one is used for 3rd party game apps, discord, sim gauges, etc.
Then I have a 1440p 27" 144hz monitor next to it for the high speed, low latency type games, which functions as main display for those games and as a secondary as described above.
This way I can show the games that dont need high refresh rates in glorious 4k res at a huge panel. When I do want to play shooters I switch to my 144hz panel, which at the size and res gives a very dense pixel density for ultra sharp images as well.
Both monitors have IPS panels.
Depending on your needs and prefs you should take size vs resolution into consideration to determine pixel density and then you need to choose what kind of display panel you prefer. IPS has deeper blacks and better colour grades, but generally has a tad slower response rates, though many higher tier models are now available with fast IPS panels. VA panels are cheaper and quicker, but often have very weak colour grading and black levels.