" ... desirable if the deinitialization string does something unnecessary, like clearing the screen."
I prefer to not clear the screen. I usually want to continue to refer to something or even copy/paste from the content to my current command line.
...And combined with some of the other options in the post, my go-to has been "less -SEXIER" for a long time. Specifying E twice doesn't seem to do anything except make this easier to remember.
git uses "less -FRX" by default. This is how I learned about -F.
(To be pedentic, git uses "LESS=FRX less", which accomplishes the same thing.)