EPUBReader as well, which is a firefox plugin, but it is plugin tool.
Lucidor is not support PDF yet.
FBReader is not support PDF yet.
Evince is not support ePub yet.
Calibre is a conversion tool also can read PDF and ePub. (run "ebook-viewer")
Okular is a good one for PDF and ePub. but it has issue for reading Asia Character.
I would live to use Calibre for a conversion, Okular for an eReader(has many useful function). and Calibre ("ebook-viewer") for reading Asia Character