When Was The Last Time You Read A Scroll?
I asked question to make a point, because I'm feed up with people comparing ebooks to printed books. Folks, they are basically same when you think about what they DO. Both printed books and ebooks hold text and pictures and are used in distribution process, it's as simple as that. Here's something else to think about, before paper people stored their text and pictures on stones.
With advancements in technologies people have come from lugging around heavy stones (that were known as tablets), to carrying rolls of cloth (known as scrolls), they then advanced to lightweight wood product paper (known as books) which can be quite heavy actually in certain circumstances. The first books were done by hand, then came printing press. And now we come to next generation of storing and distributing text and pictures (ebooks). I'm a true believer in "KISS" (Keep It Simple Stupid) principle, as an entrepreneur that happen to be in publishing business, I have too.
Why Do You Want To Complicate Things For Yourself?
I ask you this to answer your question about which format you should publish your ebook in. As I said above I'm an entrepreneur that happen to be in publishing business. So let's look at it this way, what if I was in automotive industry, what type of cars would I produce? I wouldn't, I'd make parts for all manufactures. Why? Because, I'd have a ready made market. So ask yourself, what market do I want to reach and what type of vehicle do vast majority of them drive (computer, or handheld device). Then make your part (ebook) to fit their vehicle.
Here's a tip, work on one vehicle (format) at a time or you could make a product like tires (PDF) that would fit on most makes and models. Then expand your product line in future, after your first product has been branded and sent out to pasture to get fat for market.
What Do Cattle And eBooks Have In Common?
They both need to carry your name or mark on them. As a Texan, I know importance of "Branding" or "Tagging" you do it not only to mark your property, but also so that others will know your name or mark. Sure there are rustlers (hackers) out there that will attempt to alter or remove your name/mark, but if you brand your name/mark in enough people minds it will be hard for these thieves to sell your stuff. And if they can sell your stuff you can bet they will not be getting top dollar for it. Plus they will not be doing it for a long period of time because sooner or later they will get busted.