Help finding an SFTP Server application

I am in the process of setting up SFTP communications with a vendor of ours.  After changing the project parameters from using a web service to SFTP, I have learned that IIS 8 does not support SFTP. Can anyone provide me with an application to use?

Requirements
1) Secure - Kind of a given, but I'm saying it anyways
2) Actively supported
3) Easy to use - I'd prefer not to have to do everything via command line\powershell
4) Known product\Trusted - I'm looking more for a time tested application rather than the newest latest greatest

Other
1) Can be a purchased product  - though I'm aware of several that are free
2) If it has any special features, I will be using the SFTP to mainly receive XML files into a T-SQL database

Thank you!