At work I have two 27" Dell UltraSharp monitors. Landscape on the left, portrait on the right. (27" is the biggest of the range that may be rotated using the included stand) This is good for different content types. Logs can be wide. Code can be long.
At work I have two 30" Dell UltraSharp monitors, both landscape, because they don't rotate. I have to alter my work pattern a bit to make the most of the size when I need to view some things.
The immersive feeling is good. Tiling window managers (or an application like Tilix, a terminal emulator with tiling layout) make for efficient division of screen space.