The best operating system for a VPS server may vary based on the specific needs and requirements of the user. However, some of the commonly preferred ones are:
1. Linux: This is a top choice for many because it is open-source and highly customizable. It comes in several versions, such as Ubuntu, CentOs, Fedora etc.
1. Windows: This is preferred by users who need to run applications that are compatible with Windows. Windows server may be easier for those who are familiar with the Windows desktop environment.
1. FreeBSD: This is a Unix-based OS that is known for its stability and security.
1. Debian: It’s a version of Linux known for its robustness and a large library of software.
Remember that the best will depend on what you will be using your server for, your budget, and your technical knowledge.