I would argue that 32" is enough. Maybe 35-40 if it were curved. Of course, if I could have a 1:1 aspect ratio screen which was spherical, that would be ideal. Even so, you only get so much benefit from larger size.
My primary monitor is an LG 27UD58 "4k". It is fantastic in terms of visual quality and even gaming. But as far as I can tell, there's no good upsize option. I'm hoping for improvements in VR style glasses which would allow me to look all around and see a virtual big screen on demand.
Two monitors are nice, but then you're always looking a bit to the left or right. Two stacked monitors are nice, but then you're looking significantly up or down. There's no good answer :/, other than a neural interface which does not yet exist.
However, few months down the line, this is the best decision I made for coding. The real estate makes a real difference. The quality of the panel is great and you soon get used to "bigness" and the ability to have so many split windows makes a huge difference in productivity. It'll probably really shine with a tiling WM/virtual workspaces (I use a non-tiling single workspace setup so that's just speculation though).
You still have to move few inches away if you are playing content full screen (my desk is wide but not very deep). I play Youtube videos expanded but not full screen and that is already big enough for me. For movies in full screen, I push my chair a bit away from the desk and put my legs on a small stool and then the experience is great.
Mind sharing which 43" monitor you have, and any other thoughts on its suitability for coding?