I tried both Aldiko and FBReader.
FBReader I use on my Windows desktop because it’s fast and svelte compared to using others (which, back in the day, were the Sony Reader app, Kobo app, and — god help us all — Adobe Digital Editions).
Aldiko was so slow that I became thoroughly disgusted and didn’t even waste my time with screensnaps. It’s not software I will be using.
FBReader contained an interesting and useful surprise!