As someone who loves Pink Floyd and hates rush I feel qualified to answer! (For once)
Pink Floyd write songs that have deep and relatable themes. Sonically they explored much prettier and more interesting places than rush. Their lyrics were sophisticated in telling their stories. The musicianship is also excellent without trying to sound like they are trying to show off. Even the guitar solos, are deeply melodic and hummable and memorable and serve the son musically, not just present an opportunity to try to show off. The vocals don't make me want to immediately turn their music off. They have two albums that are widely considered to be among the greatest of all time, and they also happen to sound like some of the greatest recordings technically that pushed boundaries technically and sonically.
My personal opinion is that every individual member of rush has mega talent, but that the music is very meh. But even Peart's mega talent is less than, say Dave Weckl's mega talent. And if I'm going to listen to music that only kind of scratches an itch in terms appreciating musicianship, I'm going to listen to those all time greats like Weckl and Pattituci playing together who are both much greater talents than Rush.
What I would argue is not really just a matter of opinion, is that PF is just a better band. They have a level of success, both commercially and critically, that is several orders of magnitude greater than rush has achieved.