I use two 27" 4k Monitors in landscape mode arranged vertically. That way I have one primary monitor just in front of me and some extra space when I need it.

Having the secondary screen above the primary means you won't have neck pain from looking to the one side all the time. In addition, it is quite relaxing to lean back and watch a presentation/video on the secondary screen.

The biggest downside is the position of a webcam. I placed it between the monitors with a 3D printed holder. However, that is certainly not an optimal solution.