With
Superman IV
, you can tell deep down inside, that Christopher Reeve was sincerely trying to make it up for fans who were burned by the more goofy, farcical, comedic, campy approach that
Superman III
(and a portion of #3) took under Richard Lester. It's just that Reeve was maybe, a bit too ambitious w/ his anti-nuclear arms/anti-corporate, tabloid media message.
Superman IV
was a lost cause at the end of the day, because the producers over at the Cannon Group didn't treat
Superman IV
as enough a prestige, sophisticated project (and not spread the money around for other, lesser profile projects). It's like they did all of the leg work in convincing Reeve to come back but seemingly felt like afterwards, their jobs were "finished". I don't know if Cannon really cared that they essentially released an unfinished movie just for the sake of saving a few more pennies.

I think that's the point. Comparing B&R and SM:IV is like asking who's the best dressed fat chick! Just because B&R scrubs up better visually doesn't mean it has more character.
If you dip your foot into a pool of piranhas don't cry when you lose a toe!

Production values are high on Batman and Robin, it's a great movie to look at, while Superman 4 looks like it was made for 19.99. Both scripts are equally horrible, with plot holes big enough to drive a tank through. Chris Reeve's always wonderful performance is the tie breaker for me. Superman 4 by a nose.

I haven't seen Catwoman, but I can believe it.

Something like Catwoman and Supergitl are both at a tie

This. I can't think of a worse superhero movie off the top of my head. Supergirl might be worse, but nothing else is close.