For cloud storage, Nextcloud is the best open source solution (and, I’d argue, the best solution period). I get it from Murena.io - hetzner.com is much cheaper, but I am happy to support Murena as they develop my phone OS. And I still save a lot every month compared to Dropbox. The instance provided by Murena has great OnlyOffice integration (sharing documents and working together with others works great) and an encrypted drive (vault - similar to what Dropbox used to have) enabled by default.

I use it for syncing files, contacts and calendars, passwords, working on documents together with others (collaborative simultaneous online editing works great with word and markdown, my collaborators only need a link), and really anything you’d expect from a cloud provider. I also it for a secondary e-mail account.

Part of what makes it great, of course, is that you can change service providers with relative ease, including self-hosting. Email is an exception of course, unless you come in with your own domain.