It’s not an ebook creator, it’s word processor. But something like Calibre will convert a document into any ebook format.
If you appreciate experiences, here are mine about Scrivener and IAwriter.
Scrivener is great for organizing stuff. For a research project I’m organizing text according to many countries, and it is very easy to do so, quickly move around between the various parts and search for text. I do realize there are other programs that purport to do the same, but this is the program I use. Unfortunately I do not find it good for writing. The interface seems ‘off’ to me, formatting text is more cumbersome than with other programs. Maybe I could customize it more, but I never bothered.
IAWriter is great for simply writing text. If I just want to expand my thoughts, it is a minimalistic program that just facilitates putting your thoughts in a document. However, It is not good for formatting like you want. Incidentally, I also used Bear for some time, which was even nicer to work in (it almost seduces you to write), but after I while I thought the subscription model was too expensive (it has a free use mode, though).
For actual writing I still use Word, but mainly because I need to exchange documents with others who prefer Word. I don’t like it any more than you do. I did add a few shortcuts (like one for making footnotes) to make life easier for me. Maybe some of the suggestions mentioned here would be an improvement.
So my workflow is to keep research notes in Scrivener, write raw text in IAWriter, than copy/import to Word to edit and make it into a complete manuscript.
This is all very helpful. Thank you Dope! I probably won’t start this project until the cold weather really sets in, in that uncomfortable period between too cold for long stints outdoors but not enough snow for snowshoeing, which used to be November into December but now, who knows? It’s 55 degrees F outside right now.
All I can say is that FreeOffice’s TextMaker is the least irritating word processor I’ve ever used. 
It never tries to ‘fix’ things that you type. It doesn’t assume that it knows better than you what you want. It only does spell checking etc. when you ask it to. It isn’t intrusive.
You don’t have to hunt for obscure settings. Everything is where it logically should be. It has all kinds of fancy features, but they’re never in your face. They’re just there when you need them, and not if you don’t. It ‘just works’ without a fuss.