Hi,

The best reader imho is iBooks on the iPad, nothing else, from what I've seen, comes close. But that is one expensive eReader. :(

We'll just have everybody in the world who has a Kindle, Kobo, or other reader exchange their existing hardware, and then purchase an iPad plus iBook. Problem solved? ;-)

ConTeXT TeX reading xml -> export -> optional transform -> EPUB + CSS*
you want 'direct epub html from context' (no xslt) but on the other hand use xslt to map onto context while context can do xml directly ... chicken egg

Well, given that ConTeXt doesn't actually produce validating EPUB documents, I suspect not many people will actually use that feature. It's great in theory, but if it produces books that don't actually work on the Kindle or Kobo, then it's unusable in practice -- never mind not being able to add the books to online marketplaces (such as Amazon) because, again, the output does not validate.

Kind regards.