Originally Posted by AlexBell
The University of Adelaide site has a very wide range, they're very well formatted, and they're are not derived from Project Gutenberg - at least, the ones I've read.
Yes, my observation so far puts Feedbooks and Adelaide at the top as far as combining breadth and some standard of quality. They often each have a copy of a book I am looking for. The Feedbooks versions seem to closer to true epubs, in that the Adelaide books have some html in them that works well, for example, in Calibre's reader, but not on the Nook; also the Adelaide epubs have an epub TOC with only one entry, and a full inline html TOC. Still, they are pretty nicely done.
The Project Gutenberg epubs are, in my experience, not as well put together as either of these. I sometimes store a PG epub simply as a reminder that I want to find a better copy in the future. I keep track by marking the source as PG in Calibre.
I've very recently downloaded a number of books from booksshouldbefree and epubbooks.com, when neither Feedbooks or Adelaide had that book - but have not yet done a quality check across them. I figured I wasn't the first to come across these sources, and someone would know if I was wasting my time.