There are lots of ways to read ebooks, EPub, Mobi, PDF, Word documents, and plain text being a few. But what is your preferred method? Me I read nearly all my ebooks in Kindle, so I prefer Mobi. But I'm sure there are others who prefer EPub or PDF as well. What format do you most prefer to read in ebooks?

Preferably DRM-free, whatever it is. I don’t get the number of votes for PDF–they are so inflexible. It makes sense for a comic book or something with lots of images, but not for what I consider ebooks (mostly text).
I prefer reading books with paper pages, I’m online way too much as it is with work and in need a break from electronics.
I read on the kindle or an iPad, but honestly, I don’t know which format they are.
I like pdfs. They are my preferred choice as I can read them on a number of devices. A lot of the books I reference are full colour illustrated works (craft books) – so pdfs are fine.
I prefer ePub – they display well, are easy to turn the pages of and I can adapt the text size.
I do have a lot of PDFs because many documents are available in that format – especially academic papers – but they are quite tricky to read.
(I’m reading on an eReader, not a Tablet.)
Either Epub or Mobi. I haven’t discerned any important differences between those 2. I’d give a slight edge to Epub simply because more devices seem to accommodate that format. PDFs are the worst.
My preferred method is mobi as I read ebooks primarily on my Kindle. I do have a tablet that I’m using more often. My primary issue with the Kindle is reading Technical books especially those that rely heavily on images and graphics which never seem to display properly on the Kindle. For a lot of technical books I still like to have a physical dead tree product in front of me.