What are the best native EPUB readers for *BSD/Linux. Browser add-ons are not an option.
I prefer non-Qt applications but you can share Qt applications if you want. If possible, I want a program that remembers the page I was last viewing.
I looked into this recently, and a lot of people pointed to Calibre. I think it's primarily a converter and library app, but it has a built-in viewer as well.
Try FBReader. It loads the last page you were reading by default and probably has all the features you could want. It is a Qt app (and new to the Linux desktop), but I've used it for several years on Android and it keeps getting better.
It's open source, reads many file formats, supports bookmarks, local/online catalogs, and has lots of customization options. Recently installed it on my Gnome Shell desktop and it integrates fairly well with the UI.
If you're not interested in library management and other extra features, you might want to try CoolReader. It does use Qt, but it's light, quick and very easy to use. It also remembers the pages you were last reading.
Edit: A fine alternative is the multiplatform Quivi. Also fast and sufficiently configurable. I believe that remembering what page you were on is in the to-do list so keep an eye out for it.
Edit2: I have started using mcomix. Less configurable than quivi, but still very well-made.
Lucidor is a computer program for reading and handling e-books. Lucidor supports e-books in the EPUB file format, and catalogs in the OPDS format.
I just answered a similar question and noticed yours in "related" questions sidebar.
You might find my answer helpful there: Recommendation for an eBook reader for GNOME.