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.

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.