I was still bemoaning the loss of Stanza until I discovered Yomu. And it seems to work well with Calibre and Dropbox (which is how I access my Calibre library). There are quite a lot of changes you can make to the interface - the usual stuff.. and I only discovered this morning that you can sync between devices via iCloud. Its turned off by default but it works pretty well.
I did Use Marvin for a while, and a variety of others, but Yomu has got me caught for now. PLus, it seems to be in constant development. I decided to pay for pro… definitely worth it to me.
Link:
https://yomu-reader.com/