Though I could hire someone to format my e-books, I format my own. For me, it’s a question of control.
With more people self-publishing and many doing their own formatting, readers no longer expect one ideal format. Even traditional publishers aren’t consistent in how they format their e-books. The key is to make sure the formatting doesn’t get in the way of the reader’s experience.
I use the free e-book formatting tool on draft2digital.com. I output a Mobi file and test it using Kindle Previewer. If it’s good, I upload it to Kindle Direct Publishing (KDP). Else, I continue to tweak it until I’m satisfied with the results. Draft2Digital also provides an epub file, which all other platforms use. In addition to Amazon (KDP), I also consider publishing with Draft2Digital, Kobo, Ingram Sparks, and Publish Drive.
There are also other free resources and inexpensive tools to format books. And for those who don’t want to mess with e-book formatting, there are many people who will do it for you. Check out Reedsy and Fiverr, I’ve used both for publishing-related services and had positive experiences. Another option is BookBaby, though I’ve not used them. In all cases, the price and quality vary, so proceed with care.