Another page for taking a fair look at the eReaders market is
They do extensive reviews of the machines and rate them by several criteria. If you go into the page of a particular eReader, you will see which file formats it supports (e.g., you can see that, in fact, the EPocketBook 301 supports DJVU!) and also a long, detailed analysis about how good it is for reading.
(The page looks like a little biased towards Amazon and their Kindles, though).
I recommend you navigate this site for a while before making your mind up!