The last-straw motivating reason I switched to nextcloud was because dropbox decided they wouldn't let me sync my files to an ecryptfs file system. (I believe they recanted on this policy a few months later.) I didn't like being held hostage to their bad design decisions, so I left and found a solution that worked better for me. Dropbox has also had some serious security vulnerabilities [1], which left me feeling less than confident in their ability to manage my personal data.

[1] https://nakedsecurity.sophos.com/2011/06/21/dropbox-lets-any...

Yes; I've been using Dropbox with btrfs on Arch Linux for a month or two now. According to the Arch wiki[1], Dropbox added support back for ZFS, ecryptfs, XFS, and btrfs a little over a year ago (around seven months after they initially dropped support for everything other than ext4 on Linux). That being said, I had been using Nextcloud on a DigitalOcean droplet for a couple years before that, and I never had any issues with it. The only reason I switched back to Dropbox was that Google announced earlier this year they were getting rid of Google Play Music, and I had a bunch of music uploaded from CDs on there that I wanted to back up, and I would have ended up needing to pay more per month for the storage on a DigitalOcean instance to fit all the music than the $10/month that Dropbox charges for 2 TB.

[1]: https://wiki.archlinux.org/index.php/Dropbox#Using_Dropbox_w...