Azure DevOps (was TFS) is recommended as a source code solution.
Figure: Microsoft Visual Studio Team System
Here are some of the reasons why:
Checkin policies
Integrated Work Items and Source control
Visual Studio IDE integration
Code Metrics
HTTP access via webservices
Integrated Build Server
Reasons companies choose Visual SourceSafe (VSS)
❌ Figure: Bad example - Visual SourceSafe (VSS) is a bad choice
Reasons companies choose Subversion (SVN)
It's free
It's easy to use
No Build integration
No Work Item integration
😐 Figure: OK example - Subversion (SVN)
Reasons companies choose Azure DevOps:
It's free (With MSDN)
It's easy to use
It's easy to install
High fidelity SQL data store
No VPN required
Does not require a server (basic configuration)
Has Build integration
Has Work Item integration
Has Test suite integration
Has reporting out of the box
✅ Figure: Good example - Azure DevOps