Originally Posted by HarryT
Mobi is my preferred format, because it's supported on so many different devices. I don't know what I'll be reading my eBooks on in 5 years time, but I'm confident that I'll be able to get a device which supports the Mobi format then.
That's my preferred reading format. In terms of a long-term storage format I'd choose something like RTF or HTML.
Mobi is good if you believe one book equals one file. For source documents the epub approach is, I believe a good one. A zip container with as many individual files as needed. BD does not equal one file per book either if their are images in the book. RTF is also a one file equals one book but you have to be very careful. Not all editors support all features. It is verbose text and images can take a huge amount of space.