As a number of folks have commented, it is often context dependent.
For example, photography is one of my hobbies. When editing I’ll have several applications open, in multiple spaces and using multiple monitors. I use Photoshop, so it will be assigned to one space (always the same) and the main edit window will be maximized. The tools will be on a separate monitor, and any plugins will open on the main monitor, maximized, completely hiding the main Photoshop window. I also use Photo Mechanic, and it will be on its on space, again always the same, with the browser open maximized on one monitor and the main image viewing window on another monitor maximized.
I had also recently been learning SQL. In this case I would have an online class open on one monitor, it may or may not be maximized, the SQL environment (I’m using SQLite on my Mac) on the main monitor, on one half, with BBEdit open on the other half to take notes. And then Safari or Preview open on the third monitor, perhaps both overlapping, with reference materials.
And throughout the day I may pop windows open on top of others. I may have mail open, with a specific mail message open over the Mail app, and I’ll pop open the calendar on top of a window on a second monitor to check something and then close it. Or pop messages open and closed throughout the day.
I do not use full screen, going as far as buying a license to Better Touch Tool just to make the green window button return to maximize.
Finally I use Bunch, Moom, and most recently Stay, to manage contexts and window placement. So for the examples above I have a Bunch for Photo Editing and one for Learning SQL that will open the apps, in the required spaces, and then arrange the windows how I like them. Having multiple monitors and lots of screen real estate really helps with window placement and management, although my wife laughs at my set up with all these monitors.