π Submitting your book (digital and print) with Amazon KDP? Super easy and smooth. Everything is nearly instant.
π Ingram Spark? Heh. They are super picky with files in a thousand ways that Amazon isn't. And their UX is clunky and stuck in the 90s. And it's frustrating and slow to use. Everything takes days. And ordering copies of your own book takes days. It's agonizing to deal with their system.
π Kobo? Not a bad process, pretty easy uploading.
π’ Apple Books? You gotta jump through lots of hoops and verifications and all, but otherwise pretty smooth.
β Barnes and Noble? Their platform is straight up is trash and doesn't work most of the time. Except when it sort of does. And then doesn't again. Errors every step of the way. They even say on their portal that "Due to heavy volume, we regret that we are experiencing delays in processing vendor account updates. Note these slower processing times might affect payments going on hold, new vendor registration, approving tax documents, etc." so basically don't expect to get an account online, anything approved, or to get paid anytime soon.