Hi Coral

One of the most popular platforms for selling is Ingram Spark. But before I engage in that terrible debate... There are many practical issues to creating a great paperback. Having published 5 of my own, and also in doing formatting and book design for fellow self publishers, I recommend never using them "convert to paperback" options on websites like KDP, ISp, D2D and so on. That's because the formatting of a paperback works quite differently (Which I know you get, as a reader). The first important thing to do is have your book interior formatted for paperback printing. There should be no difference at all between printing with a local company, or using a Print On Demand like KDP. It's important to remember that YOU are the publisher, not KDP. Amazon KDP is merely a printer and distributor, and of course a sales platform. Your book will get no physical, human interaction. Yeh, Amazon will claim it does, but pfffft to that. Since I don't know how far you are with formatting and designing your paperback, I'm skipperoo to an important end point. One of the design aspects that trips many authors up is the COVER design - not the arty bit, the physical bit. This has to be done as a SINGLE cover which wraps around the book, and includes the Front, Back, and spine. Sadly, all of the companies print is paper with the teeny-weeniest different in thickness, so there are differences found in Spine Widths from Amazon printed books and the rest of the industry (I tend to find Amazon print fatter books! Anyhoo, if you need any help with your paperback design, zap me a message on here and we can chat.

Good luck.

Colin