I moved to Tresorit, and so far it’s been great. It’s end-to-end encrypted/zero-knowledge. The service is a little bit enterprise-y, but really solid. I’ve done all I can to test and and haven’t been able to flaw it. Merge conflicts end up as duped files, just like Dropbox, which is great.

Their Mac app is good. It’s native and doesn’t use a ton of resources (I haven’t used it on other desktop platforms). AFAIK, it doesn’t support APFS extended attributes, so Finder tags won’t get synced. It does use the Finder sync extension API though.

It works slightly differently to Dropbox — rather than just being a single folder that syncs, it’s more like selective sync, where you have multiple folders that are optionally synced. This confused me a little during setup, but I think I prefer it now.

I tried pretty much all the other alternatives and didn’t like them. I’m already paying for iCloud Drive, so I’d love that to work, but it’s chewed up files or taken hours to sync on too many occasions, so I don’t trust it any more.