Firefox is still pretty ugly, too. On macOS, it feels chunkier and less natively integrated.
Safari's "omnibar" is superior to Firefox's. Safari actually suggests web sites, which I use all the time. Wikipedia is a major one. Start typing "Richard Fey", for example, and the first hit will be the Wikipedia page for Richard Feynman, complete with a short summary and photo. Firefox forces me through a Google search.
I also tried out Firefox on iOS some time ago, and it wasn't as nice as Safari. For there to be a point to this, I'd need the same browser in both places, with perfect syncing of bookmarks, cookies, tabs, etc., just like Safari.
Lastly, migrating is a pain. There's apparently no way to import my current Safari session (I have probably 60-70 tabs) or history (I keep everything I visit, going back years), which means I'd lose stuff by migrating and would have to migrate tabs over incrementally. Hard to try out a browser in any significant way this way.