We use standard GitHub-hosted runners for CI/CD jobs. Most of our tasks use Ubuntu-based runners and they should be preferred when action doesn't require some specific OS/hardware platform. Since in general runners are limited hardware-wise actions should use the minimal required version of the runner. As of Dec 2025 this means using ubuntu-slim if possible for the task.
Using "latest" version of runner (and OS respectively) is preferred unless there are valid reasons to pick any particular one. Usually "latest" is the most widely available version and actions can't get obsolete because of missing runners this way and we get more uniformity between different system components. While theoretically it can bring some instability because of OS updates practically it's rarely a problem and even some problem happens we better know it sooner than later.