Although it's been a while since this question was asked, I thought I'd toss in my two small coins.
Activ Ebook Compiler was the first compiler I used way back when. We're impatiiently awaiting Sunil's next upgrade for it. We've bombarded him with a huge list of wants Can't wait for him to finish and release version 5!
I've also used Ebook Publisher, Ebook Creator Lite, Easy Ebook Creator, Hiebook Builder and the MSReader build for the lit files. Ah, and several PDF creators. Of those, I use Adobe Acrobat, PDF Writer which comes with Word, and whatever PDF creators come with WordPerfect and PrintShop Pro 15. I also use PagePlus on occasion, and it has it's own PDF creator as well.
Since the PDF creators in the other programs are pretty good, I mostly use Acrobat to clean up my files, and I'm very glad to have it to do those tedious tasks
While I'm getting more proficient with PDFs, and am having a great time learning to make them more interesting, my favorite compiler is Activ Ebook. Sunil's got some nifty add ons for it as well. Cool stuff! If you'd like to see what I've done with it, download one of my sample chapter eBooks at Each book is designed a little differently. There's also one in PDF.