I’m currently using readera but it’s not that good (text scaling is behind a paywall)
Edit:the ability to put stuff into categories would be neat btw
librera
Librera Reader (Book and PDF reader) https://f-droid.org/packages/com.foobnix.pro.pdf.reader/
I’ve been using this a few months and recommend it as well. It’s serviceable but feels a bit janky. Scrolling and switching between view styles tends to leave black boxes on my device, and the UI doesn’t always disappear while scrolling. But I’d still recommend it for how light and fast it is on top of being FOSS
That’s what I’m using:
https://gitlab.com/mudlej_android/mj_pdf_reader
I would advise to use open-source software wherever you can. You (almost) never have paywalls, ads or trackers there ;)
I had Readera Premium purchased 3 years ago when I wasn’t aware of really great free softwares’ existence. I had bought it because of it’s simple interface and thought it could help me with OPDS (auto sync between devices or other apps), but it didn’t help me other than by just being simple. That’s why I am currently hosting my own OPDS server (Kavita) to sync my progress and read from it’s web interface and Librera app (really powerful and open source). I am thinking of moving to Calibre Web from Kavita because of ease of uploading books. You can try Librera which is a really great and powerful pdf/book viewer/reader with/without OPDS.
Try KOREADER.