As a few people have pointed out, Kavita is a solid one. I ultimately used it because it saves your spot in the book server-side instead of with the browser (like calibre-web) so you can pick up where you left off on different devices.
Also has a pretty good PWA for your phone if you want to read on there.
I wouldn't consider myself a power user on ebook servers by any means, but I spun up Kavita a few weeks back and it definitely handles everything I need it to so far. Feels better to use than calibre IMO too.