I'm a happy GitHub user, these things I'd miss from pure git:

- Search (across code, issues, pull requests etc)

- Issue tracker (~ manage my backlog, write down potential ideas)

- Pull requests, review UI around them

- GitHub Apps and Actions (~ automation) and integration with third-party tools (auto-deploy changes to zeit.co / netlify / heroku etc).

- Security audits (GitHub can send pull requests to bump my dependencies when security vulns are discovered in them)

- Ability to contribute without having to fork/clone/push changes (I quite often contribute to projects by editing the code directly through the GitHub website).