[GoghGirl]

I have never used aldiko so I really cant compare the experience or features.

I use FBReader and (more recently)Moon+ Reader. You can move both of their directories to the Calibre Companion so you dont have to worry about losing your place and bookmarks. Unfortunately each app only remembers where its own bookmarks and where you left off reading so switching between them isn't an option in the long run.

I suggest you try both of them out!

Both have the basic features:
-Bookmarks
-Night/Day screen (light text on dark/dark on light)
-lots of fonts/colors
-recently opened books tab
-easy selection for choosing a different chapter
-probably missing many features than I don't generally use

I don't use annotations or bookmarks but it seems Moon+ might have a more sophisticated bookmarking tool. I also like Moon's smooth scrolling. You can flick through an entire chapter without turning a page. However I prefer RBReaders simple design compared the the flashier and more complicated Moon+.

If you do try out FBReader. After you change the directory it may not work immediately. It took at least a restart for it to start accessing Calibre Companion.