When comparing BitTorrent Sync vs SpiderOak, the Slant community recommends SpiderOak for most people. In the question“What are the best personal file-syncing solutions?” SpiderOak is ranked 8th while BitTorrent Sync is ranked 14th. The most important reason people chose SpiderOak is:
Thus you have a single service for all of the things.
Specs
Ranked in these QuestionsQuestion Ranking
Pros
Pro No service cost, storage limits, perfomance limits or privacy concerns
Since BitTorrent Sync uses P2P technology and does not require an external server from a third party, the only limitation if what is available to the user.
Pro Clients on most platforms available
BitTorrent Sync is available for Windows, Mac, Linux, Android, iOS, Windows Phone and BSD.
Pro Self hosted
If user opens a malicious website that website may create users to access your data ("When registering, http traffic for creating new user on loopback http://127.0.0.1:8888"). Being self hosted one does not need to open a site to get to their files.
Pro Combines cloud syncing, storage service and backup client
Thus you have a single service for all of the things.

Pro Available for many platforms
The Spideroak client is available for Linux, MacOS, Windows, Android and iOS.
Pro Incrementals
SpiderOak updates only that part of the file that has changed, saving bandwidth and time.

Pro Zero knowledge
Data is locally encrypted before uploading to Spideroak. They cannot recover your data even if they wanted to since it is stored in encrypted state on their servers.
Pro Unintrusive
Cons
Con Proprietary
Being proprietary, it's harder to audit.
Con Has some risky attack vectors
The only really good thing it has is that data is self-hosted (i.e. hosted on a server running on your machine with data that are on your machine).
- If user opens a malicious website that website may create users to access your data ("When registering, http traffic for creating new user on loopback http://127.0.0.1:8888")
- GetSync.com server receives many (all?) hashes in cleartext when sharing the directory.
Con Pro version for a fee
Selective Sync only available in Pro version. Business use is not allowed with free and Pro versions.
Con One peer of your network always has to be online to propagate changes to the other peers
Con Android app drains battery fast
