Firefox is my default browser anywhere but macOS, owning an iPhone and iPad I end up using the continuity features in Safari quite heavily when I've been browsing something on my phone or tablet and want to pick it up on my iMac.

I love Firefox, and owning an iMac I'm not terribly concerned about the power efficiency difference between the two - but damn if it isn't convenient to have the ability to just pick up where I left off.