SFTP vs. FTPS

We already interact with two partners using sFTP/OpenSSH. A third partner has given us a list of connection methods that they support and they have listed sFTP as well as FTPS. Given that FTPS is native on wM 6.5 would you recommend going with this connection method instead of sFTP? Can you recommend any whitepapers or reading material that compares the two?

Thanks,
Harry