I refer to it simply as “Star Wars” in most situations, just because that’s the name the movie had when I first watched it. So that’s what it’s called in my head. Anything else requires me to make some effort to translate.

The exceptions would be:

if I’m specifically referring to the fugged about with version
if it’s in the middle of a conversation about the wider Star Wars universe
In both those cases, I’m likely to refer to it as “Star Wars - A New Hope”.

I never use the Episode IV bit; not for any principled reason, but just because Star Wars is too deeply embedded in my soul as “the first one”.