[renke1]

The best thing is that it does not seem to hard to extend KOReader to your liking (e.g. by writing plugins). On the other hand, I've had a hard time understanding the the actual Lua code (most likely because of my lack of experience using Lua though!).

What's really missing is a good way to browser by metadata (e.g. author, series or even your own custom tags). However, there seem to be some progress here [0].

[0]: https://github.com/koreader/koreader/issues/8472