I did a pretty deep dive for my company recently. We are very data-privacy centric. Here was my Lemmy post on it: https://lemmy.world/post/51963153

Some of the items there are mentioned here, but after the evaluation, my hunch was correct and we are likely switching to https://runbox.com/

Good service, pricing, privacy focused but not so much that you need to host your own proxy like with Proton, and runs sustainably.