We are changing our system. We settled on git (but are open for alternatives) as long as we can selfhost it on our own machines.
Specs
Must have
- hosted on promise
- reliabile
- unlikely to be discontinued in the next >5 years
- for a group of at least 20 people
Plus
- gui / windows integration
For the server I’ve used gogs for many years. It was easy to set up and has a web interface. What client you use is really up to you with git.