If the rest of your stuff is also Apple, browser sync is a pretty solid Just Works thing, which can be a benefit of using it, but you're not all-Apple, so that benefit's out.
[EDIT] "So what are the downsides?" worse dev tools, worse add-on ecosystem. Sometimes it's missing engine features that FF and Chrome have (this never hinders me at all in practice, with my usage patterns, and in fact I'm usually glad when they choose not to uncritically and promptly implement every single feature Google adds to Chrome, but I understand it bothers some people a lot, so would definitely count against Safari if those features are things you really want/need)
It also feels so much faster. Maybe the others have caught up on the Mac over the years. But it used to be night and day.
I even use it for development. The dev tools are fine for me. I agree FF/Chrome are better, so I use them when I need it. Especially for the React or Redux plug-ins.
But for standard JS errors and CSS tinkering I find Safari works just fine.
During my own Great Browser Migration, part of my motivation for going from FF to Chrome was that Chrome caused fewer beachballs when I wasn't even using it (I'm a tab hoarder, so it's my own damn fault, kinda). My switch to Safari came when I realized it almost never caused a beachball (plus the huge battery life improvement).
I'd hope Chrome and FF have both gotten better (this was about ten years ago), but I still use FF off-and-on (though mostly on Windows) and my sense is that it hasn't improved a ton on that front. My understanding is you can fix much of this with various add-ons, though, at least on Firefox (less sure about Chrome). The Great Suspender, stuff like that. I've not used them, though.
Thanks someone for bring it up. More features Chrome add are in the larger scheme of thing invates our privacy, WebTorrent (leaks IP addresses of the other peers). WebGPU leaks hardware info finger printing, etc.
By using web browser I expect some sort of sandboxing. Why do I need all these features in a document based viewing portal?
There's a pretty slick tab grouping interface but I always forget its there.
The swipe feature also makes more obvious, but easier to work around, bugs in the open in new tab -> back button feature (which is also awesome, when it works).
it's taking all of my willpower to learn to use two-finger-swipe back instead of my lifelong muscle "right click" "back"
whats the new tab -> back button feature?
By default if you open a new tab from a link (either intentionally or by clicking a link which opens one for you), Safari adds the linking page to your history for that new tab. If you click back, it’ll close the tab and take you back to your previous state in the tab you left. It works really well when it works, but often leaves zombie tabs open with unclear history if you navigate around in the new tab.