21:9 ultrawide for main desktop and gaming and 16:9 to the side for discord, browser, whatever else is plenty for me. Also that's all that will fit on my desk arms lol.
Similar set up for me. But 21:9 is my desktop, so discord, web browser, anything that is lower quality. Then my 16:9 is my gaming and high quality content screen.
This is because my 21:9 monitor is a bit older now, and a 144hz VA panel, and I hate it for games. My new 16:9 is an OLED and 240hz and it is absolutely gorgeous. I also mostly play fighting games, so anything more than 16:9 is just black, well in the case of the VA panel grey and a bunch of light bleed.