I'm surprised no one mentioned LibreOffice Draw - it doesn't always work perfectly (I guess it doesn't support some parts of the spec), but when it does, it's by far the most powerful pdf editor I found allowing to do things like move elements around, edit them (as in actually edit, not just annotate), etc. It's cross platform and FOSS.
For page-level edits (rotating, reordering etc) pdftk in the cli (+ChatGPT to find the right incantations) works very well.
The problems with PDFs I encounter, however, are large scale 1000 page PDFs that compile PDFs from multiple sources that clearly have multiple different types of encodings, fonts, etc.
I'd love to have a pipeline that properly 'shrinks' everything. Not sure thats what this thing does, but it looks like they're moving towards configuring pipelines that could get there.
For page-level edits (rotating, reordering etc) pdftk in the cli (+ChatGPT to find the right incantations) works very well.