Don't use anything now but am interested. So I made a list of alternatives used/recommended by HN citizens in this thread and thought I'd share.

  Copy
  Wuala
  syncthing (foss)
  Bittorrent sync / btsync
  Seafile
  Box
  Expandrive
  rsync.net
  pcloud
  Tresorit
  Google drive
  Hubric
  Amazon S3
  onedrive
  SafeMonk within Dropbox
  Spideroak 
  owncloud 
  Tahoe-LAFS