My vote is Archlinux. Debian is sometimes a little too “optimisitic” when backporting security fixes and upgrading from oldstable to stable always comes with manual intervention.

Release-based distros tend to be deployed and left to fend on their own for years - when it is finally time to upgrade it is often a large manual migration process depending on the deployed software. A rolling release does not have those issues, you just keep upgrading continuously.

Archlinux performs excellent as a lightweight server distro. Kernel updates do not affect VM hardware the same they do your laptop, so no issues with that. Same for drivers. It just, works.

Bonus: it is extremely easy to build and maintain your own packages, so administration of many instances with customized software is very convenient.