Installing VirtualBox is getting increasingly painful on Ubuntu due to the problems with UEFI Secure Boot and the VirtualBox kernel modules. Another reason for an alternative is that running VirtualBox VM’s completely in the background is not as straightforward as it could be.

From the available alternatives I looked into (VMWare, Xen & KVM) it was KVM that fitted my needs (casual VM usage with mostly headless VM’s for testing purposes). Main reasons: