How extensible do I want a web browser to be? I have 1password and adguard but otherwise I'm not that interested in loading stuff in that can read all my browsing (e.g. grammar.ly...I just learnt to write instead). There's enough spyware as it is.

Safari is pretty fast and very good on battery life. I like that it has the same bookmark store and accessible tabs across devices.

And there isn't a lot of alternative. Firefox is slow. Chrome is a memory and performance pig; I run it only if I happen to use a google service for some reason and don't let it save any state.

That's a great question!

I switched to macOS around the time Yosemite came out and I didn't use it back then because it wasn't great but honestly it's improved a crazy amount to be a really nice daily driver as far as performance / battery use is concerned and it's integrated with iCloud which makes moving the browsing session onto mobile and back really convenient and also adds the keychain. On top of that the general browser experience with the way it implements gestures, etc. feels very cozy on the platform. So it's a case of compromises between good and bad.

I sometimes use Chrome (well, Brave), too. Very rarely Firefox, which I don't really like using for much outside of development and testing.

iCloud Keychain and Syncing with iPhone.

Those, plus battery life and noticeably more overall respect for system resources, here. FF and Chrom(e/ium) aren't even close. Which is too bad, because I'd like to have decent plugins again, but it's not worth the cost.

I'm a 1password user and apple has really allowed it to be a good first class, cross platform participant in login interactions on ios and macos. I disabled the apple-managed password and autofill options.

Yes, indeed. The keychain is kind of a big selling point. I'm planning to try and move onto BitWarden to keep my password management cross-platform and open source but it's not as well-integrated. It would be way better if it could sync the iCloud credentials instead of manually having to jump through hoops to get them in.

The Apple lock-in with my passwords makes me feel uneasy and probably way less likely to consider using other platforms as often for daily tasks.

And SMS code filling

Because it inflicts the least cruelty upon my hardware.

Because it syncs bookmarks and passwords through iCloud.