Mono. Hands down no contest.
The irony is that everyone thought of Star Wars for the Dolby Stereo or the 70mm baby boom bass enhancement-but no officials ever thought that theaters would seriously implement Dolby systems across the board. The mono mix was done last and was intended as the keeper track for general wide release and was thus heard on most prints throughout the country for the rest of the long run.
You do find yourself missing some of the stereo mix identifiers and the stereo separation, the mono rear surround and more technically advanced experience…but then are confronted by what I think may be the pinnacle of single channel film mixing. I even think the score is better mixed in the mono in terms of levels and balance and of course it immediately makes a direct connection to adventure films and serials of old which were also mono.
Jaws had already shown an amazing mono mix for 1975 and then along comes SW which goes far beyond that-but of course now this mix is lost to time in the general populace and its fixes were implemented into the 1997SE mix which was then bastardized and ruined in 2004, 2011 and 2019.
The monos for ESB and ROTJ were more intended for 16mm and other editions but the mono ESB is another custom mix with differences stemming form the 70mm mix in places and some things turned up in the 1997 SE mix again. ROTJ is more of a folddown from the Dolby Stereo.
This carried over into Indy where Raiders also has a custom mono with line differences, Temple has a mono presumably designed for 16mm and I think was the last custom designed LFL produced mono track.