I haven't spent much time with calibre-web in a long time but can confidently say BookOrbit blows it out of the water in terms of functionality. I love that I can have one app that handles books and audiobooks. The ecosystem of apps that work with it is growing quick too, Apogee for iOS being a standout for me. They recently added readaloud support (like Amazon Whispersync or Storyteller) natively in the app, which I've never seen done before.

I have no relation to BookOrbit except I'm a very happy user.

The storyteller mobile apps have supported readaloud for years. You can even set different playback speeds for readaloud vs listening, so when you background the app or lock your phone screen, it will switch from the readaloud speed to the listening speed. I typically use like 2.25x for readaloud and 1.5x for listening.

I don't think calibreweb is that old, are you thinking of the calibre webserver?