Danger on Ruby is more mature, has a solid plugin eco-system and is very stable. It supports Ruby 2.0 and above, and will likely work on any CI setup without additional work.
The project is on version 5.x with about a hundred releases, that’s a lot of battle testing. I consider it in a great place and is unlikely to have breaking changes from this point onwards. The GitHub issues to number of downloads is really healthy too. Almost 10 million downloads now and a new issue maybe once a week.
I have no intention of ever deprecating Danger Ruby. If you’re using it today, you’re fine to stay that way.
Get started with Danger on Ruby.
If you’re working in a Node environment this is definitely the right choice.