(I need to post more often and like, practice actually posting things that come into my head, hence this.)
One of my favorite things about Ao3 probably belongs under the category "pathetically grateful," but I just love having text-formatting options.
Back when I had my own fannish website, I could do it any way I wanted, of course, but I'm comparing to FF.net, which I don't despise, but gods dammit, why are you terrified of my typographical choices? AFAIK my old (as in "wrote these in high school") FF6 stories are still sitting on FF.net looking like s**t because they stripped the em-dashes and whatever I was using for scene breaks or some such idiocy and I'm too embarrassed to look at the stuff to go back and fix it.
So yes, Ao3 is like WHEEEE! CREATIVE FREEDOM!
I can use scene-break markers of my own choosing! I picked some of those for reasons! (Fushigi Yuugi: The Mirrorverse
uses seven asterisks --- seven stars, 'natch. Seven Year Promise
uses seven asterisks if the POV is changing and only one if it's not to suggest a harder or softer break. My Allison & Lillia stuff
uses a pattern of asterisks that stands for the two "first generation" couples on either side and their kids not quite meeting yet in the middle.)
I can use blockquotes! I never needed them before, but dang Wear My Fearsome Power
looks nicer that way --- being that big sections of it are being read out of a book in-universe and all.
I can make links and not be suspected of being a cyber-terrorist! I tend not to use them in the story itself, but it's so nice to be able to put them in author's notes.
And I can tell Ao3 to insert white space and it ACTUALLY ****ING DOES IT WITHOUT STRIPPING IT OUT. I can use THAT for a scene break if I want! White space was a big high-concept deal in Seven Year Promise of course, but the fic I'm drafting now just has kind of an ending and then a little "hours later" coda and it just feels right to use a longish white space there AND I CAN JUST BECAUSE.
On Ao3. On FF.net, nope --- horizontal rulers, that's all you get. (Not that I don't love horizontal rulers but THEY ARE NOT ENOUGH FOR ME.)
So yeah. I'm not down with FF.net hate for the most part, but this is why I've declared it a "deprecated mirror" for my work.