PDFs are exact representations of the page as the author intended, EPUBs are not. I generally find PDF far superior for nonfiction because it often has diagrams, pop out sections, etc. EPUB is fine for novels.

I'd rather not have the diagrams as the author intended, but more like my device intends. PDFs are great if you need a digitalized representation of paper. Epubs are great if you want a website structured like a book, which is exactly what you want most of the time when you have an e-reader. I'd prefer not seeing diagrams as the author intended to not being able to scale the font.

It's a tragedy that PDF to Epub conversion is generally not that good, I really wish more publishers (and selfpublishing authors!) would consider selling epubs as well.

PDFs don't really work on my kindle.

A lot of people don't like reading technical material on e-readers where the structure of the content can be manipulated and diagrams altered, so they prefer PDFs to keep that formatting intact.

I think the biggest problem is why ereaders don't have proper support for PDF.

At least I am yet to find one that can handle PDFs as easy as epub/mobi.

Somehow I suspect it is related with royalties to Adobe.

Well iPad - iBooks have a proper PDF support isn't that enough?

No, because it isn't e-ink.

Reading standard screens is impossible in full daylight and also leads to sore eyes.

That may have been true five years ago, but it isn't really true today. It's been a really long time since I've had to cover my phone to read something on it, or needed to go inside. Screens have definitely gotten better in the "reading in the daylight" category. But E-Ink hasn't gotten much better in the "reading in the dark" category.

Never owned an iDevice and never will.

That's usually the case, but I was pleasantly surprised to read this book on my Kindle. The A5 format is quite readable, if you don't mind some of the tiny font size (I actually like it).

neither do epubs..