Originally Posted by astra
LRF without a shadow of doubt.
Since doubt doesn't actually have a shadow we'll go with ePub since it's actually a better format and works better then LRF. With the new Reader Library or Calibre, when you put LRF on the Reader, the Reader has to calculate the pages for every font size. ePub is also way way faster when you have embedded fonts. I'm not sure how fast LRF with embedded fonts would be on the newer faster Readers. But it probably is still slower then then ePub.
LRF.. if you ever get a device that reads eBooks and it's not from Sony, LRF will need to be converted. Most Readers/computer/tablets/iPhone/Android can handle ePub.