From what I can tell it’s not just our household that prefers the left side menu over the top menu. It allows you to navigate in fewer clicks, and it is just nicer.
If you have to have a top menu, because of some specific device that I’m not using (we use the PC, TV, Phone, and Gaming Handheld systems, and left side menu is better on all those) - then keep it as an option, but allow for toggling back to the navigation system so many people have come to love on Plex over the years.