Should I use VirtualBox or KVM/libvirt to quickly run a server on Ubuntu 24.04?

For a server guest, QEMU/KVM with libvirt is generally the better long-term choice. KVM is integrated into the Linux kernel, usually gives better performance with lower overhead, and Virtual Machine Manager provides a straightforward graphical interface for creating and managing VMs.

The choice depends on the guest workload. KVM is a strong fit for servers, while VirtualBox can have advantages for graphical desktop guests because of its graphics drivers and relatively easy bridged networking. Virtual Machine Manager makes the KVM setup much less intimidating than using command-line tools.

If by “server” you mean a lightweight service rather than a complete operating system, containers could be another option. Docker or a similar container tool will start faster and use fewer resources, but a full VM is safer when you need a separate kernel or stronger isolation.

VirtualBox is probably the quickest option if you just want something simple and familiar. Its setup is beginner-friendly, but KVM tends to be more efficient. For server workloads, I’d choose KVM; for a fast one-off VM, VirtualBox is still perfectly usable.