SpiderOak isn't "better" than DropBox. It supports privacy but the service and support is utterly appalling.

I was getting upload speeds on the order of kilobytes per second on a gigabit fiber connection while my CPU was idling. Filed a support request and they bumbled around a bit and then ceased responding to me entirely until I opened another ticket and demanded a refund. It took 5 __months__ to get to this point, with them not responding for weeks at a time.

I'd recommend something like https://www.syncany.org/ over SpiderOak any day.