What's wrong with Github?
IMO being able to do everything from Github is a huge advantage, not a disadvantage.
SW development is already hard enough, we had to use tens of tools even for a simple project, so if it possible to avoid new tools/services, or use a mainstream one, even if it's not as fully-featured as a specialized tool.
Occam's basic rule was "Thou shalt not multiply extra entities unnecessarily".
Everyone already has a Github account. You can add any external collaborator with a single click.
Everything (issues, PR, releases, etc.) is super-customizable with templates.
You can do any SDLC or Project Management with Github alone.
- You can do Kanban with new Github Projects.
- You can use TODO task lists and convert them to Github issues when needed.
- I even implemented Shape Up method in Github with scopes and tasks[1]
[1]
https://basecamp.com/shapeup/3.3-chapter-12