1. Buildkite is probably the best commercial, off-the-shelf CI system right now, in terms of providing all the correct building blocks at the correct level of abstraction. 2. The impact of your CI system itself being good or bad is tiny in comparison to everything else in your end-to-end CI workflow. Far more important are your own CI scripts and what they run. A distant second is the observability tooling around your CI. 3. It's hard to justify the per-seat pricing of Buildkite, as a separate line item, when whatever CI offering your source control host bundles in will suffice.