Neither. The single app that Proton has done somewhat right with is their VPN and only because they haven't eliminated port forwarding. Everything else they've utilized non-standard protocols and failed to provide source code or API docs. They basically said that users are too stupid to protect themselves, and that you should just trust them to do it for you.
They failed to provide CalDav & CardDav syncing for things like calendars & contacts, IMAPS for mail, and prioritized things like their cloud-only password store. They had no valid reason not to use standardized protocols other than to prevent their users from actively syncing local copies of their data to integrate with privacy-friendly open source software. They act like Apple & a lot of their users prob. are Apple fan bois who will trust a company no questions asked. I have no reason to trust them whatsoever.