I bought fbreader premium on android 10+ years ago and have never regretted it. There's also a PC port but last I checked it was a little out of date.
Edit: Misunderstood the question. I'm using an Alldocube iplay 50 pro as my reader. I've got my kids set up with old best buy branded 10" android tablets that were always turds but surprisingly good as just barebones ebook readers. I'm a US product reviewer for Umidigi and they're sending me a G1 tablet to review this week, for the price it definitely looks promising.