I've also made the move to Zen. I think Arc users will feel right at home there. It hasn't quite reached he same level of polish just yet but being in active development is a big plus.

On top of that, Zen can be personalized with CSS. As someone who spends a lot of time in the browser, it's been awesome to be able to tailor it to my needs. https://docs.zen-browser.app/guides/live-editing