To throw my hat into the ring: I've found the best "runnable jobs" / "digraph of jobs" system I've ever used to be Gitlabs built in CI system. The UI is nice, it's got tight integration into our existing code workflows meaning there's a close-but-not-too-close association between code and jobs meaning it's easy to say that "the code and the jobs running that code live 'in the same place'" if you want that, and it still provides all the pipeline features you'd want if you want to use your CI/jobs as a cornerstone of your infra; features like the ability to schedule pipelines, to trigger pipelines via other pipelines, remote triggering of pipelines via cURL request, pipeline DAGs for a 'make-like' build experience, etc.

I've absolutely loved using Gitlab CI for the last several years, and I highly recommend it.