Welcome to the forum. Although many of us do read e-books, most members of this forum would think of themselves as e-book authors and we would typically use an e-book compiler/generator to produce an e-book. (an e-book reader is a program designed to display the content of some e-books).
When I first started looking for an e-book compiler I had a long history with computers and programing. This gave me a different perspective than most potential e-book authors.
First of all, my experience made me mostly immune to the hype, deceptive advertising tricks and exaggeration that many e-book software companies use to attract the uneducated consumer. I wanted a detailed feature list and some way to compare the products... So, I did a lot of testing.
Unlike many Newbies, I understand a potential e-book customer is much more interested in content than packaging. Newbies often make the mistake of thinking that their success depends on the style or looks of their e-book software. They also have a misconception that a Super Maxima Compiler with an expensive price tag will help them sell their product. Not true. No matter how impressive your e-book software is -- if potential customers are not impressed with your content -- they'll ask for a refund.
Therefore, the design of any e-book compiler should appear to be simple and straight forward with well organized browser style interface components. The potential end consumer should be able to "instinctively" move through the contents of the e-book document. It should also be pointed out that most consumers dislike "logging in" or online monitoring.
Out of all the potential e-book compiling software I tested I chose the Activ E-Book Compiler. Not because it was the cheapest -- but because it had the best feature list I could find. Most e-book compilers/generators offer a list of similar features but only Activ E-Book includes it's own scripting language called Activ Script.
Newbies might not recognize the benefit of such a feature but authors who want to publish e-books with interactive content should pay attention. Activ Script not only gives an e-book author the ability to save session data (such as test scores etc.) it also gives you the ability to create real multi-media software programs and games. Authors producing educational e-books will find this feature particularly attractive.
In addition, I market software called HYPrLock which extends the Activ E-Book feature list in ways no other e-book software can match. With HYPrLock, authors can distribute self-secure e-books, self-secure CD content and self-secure PDF content (self-secure = security without online database, expensive charges or monthly fees).
I hope my comments give you some of the insight you were looking for.