I thought it would be useful to compare FTPS with SFTP and provide an
explanation of when to choose one over the other.
FTPS takes all the logic of FTP and applies SSL to secure it,
which means separate signaling and data channels.
SFTP is more firewall friendly and only uses port 22
with a single TCP session overall.
FTPS traffic looks like FTP,
meaning that quality of service or traffic engineering
applied to this traffic is relatively easy.
SFTP looks like SSH traffic,
making it difficult to distinguish from interactive SSH shells or SCP transfers.
FTPS uses digital certificates,
implying it can be easily integrated with an enterprise CA or other PKI system.
Managing SSH keys for public key-based authentication is possible,
but often more difficult.
My general advice is that if you control the server,
client, and network in between,
FTPS is a good choice since firewalls are less likely
to have extremely strict policies,
and you may want granular control over QoS for FTP flows.
If you are working outside company boundaries,
for example, SFTP is nice since firewalls can enforce a simpler policy, keeping everyone's network a little more secure.