Amazon
It's hard to get away from the Amazonian juggernaut (the company, not Wonder Woman), and it's not necessarily something that I want to do. But I am learning that this is a complex process, and not everything works with Amazon.
All of my novels are now exclusive to Amazon and are enrolled in KDP Select. I am starting to see some sales and some reading done in the Kindle Unlimited space. I put 111 Souls up for free for 5 days and had 200 copies issued or so, which is far better than I ever did leaving some of my books for free up on Smashwords for months at a time.
I am finding that poetry might not be something I need to keep exclusive to Amazon as a) I tend to give poetry away for free and b) people on Amazon don't seem to want free poetry. I'll wait and see how Solar Tempests fares, but I was getting anywhere from 5-30 downloads per day on Smashwords with two poetry books. In 4 days on Amazon, Twenty-Six Suicides has gotten 16 downloads, and you can only give a book away for free 5 days out of every 90.
Once this 90 day period is up, I might go back to making the novels exclusive to Amazon, but collections available everywhere. Nobody really buys poetry anymore, so there's little sense in trying to sell it, and the whole point of giving it away (other than someone hopefully enjoying it) is to entice people to come look at everything else you've done.
So much more to do though. Several books to edit and get available; Amazon offers a program called CreateSpace for getting hard copies of your books published; submitting my screenplay perhaps to Amazon Studios.
Faring onward...