We have strict data sovereignty requirements, so we do a lot of self hosting. We are also a kubernetes shop, so we've been using the Argo-CD / Argo Workflows combo. I quite like it, there's a lot of freedom to spin up a container and do anything you want in it while passing results to the next step, it might be too much freedom for some folks though. CD systems have some variety to them since there's so many ways to deploy code, but CI systems all feel pretty similar to me. The main differences are the format of the instructions you write for the system, and how much or how little it holds your hand.