Nothing comes close to Safari battery life on MacOS, followed by chrome, followed by firefox in last place (with all its other issues - those claiming otherwise have stockholm syndrome). I've tried taking Orion for a spin which should offer the battery life of Safari with the flexibility of running FF and chrome extensions - but it hasn't stuck yet. As much as I'd like to use FF, I really don't want to shave 10-20% (?) off a battery charge cycle when I spend 90% of my day in the browser.
[1] https://www.reddit.com/r/uBlockOrigin/comments/1lx59m0/resto...