None of the services listed are open source, so that is a red herring. Open source isn't even particularly important here, because your data isn't locked into any kind of a format - you can switch freely to any service at any time, and you have a complete copy of your data at all times. If you really need open source, there are options which require a server: SparkleShare works well for me, and I understand that OwnCloud has something that works decently as well.
My problem with the service is that it works poorly in a mixed-computing environment. It loses xattr between Mac and Windows (and probably Linux). It has some pretty bad behavior when faced with a filename that only differs due to case.