I just started testing Keybase filesystem. Looks promising so far. Everything encrypted, 250GB for free (for now). Sharing folders with my coworker works seamless.
The advantage over Dropbox is that it does not take any space on your harddrive. Also everything is encrypted by default.
A disadvantage is that your data is not available without internet, since it works like a network drive.
https://keybase.io/docs/kbfs