I am going to have a new server that run Plesk Onyx because I saw this control panel is low price and easy to set up and use. What is the best web hosting to run Plesk Onyx? which server specs should I consider to run Plesk Onyx best?
About server specs, I think a VPS with at least 2 vCPU and 4GB RAM will be an excellent choice to getting started with Plesk (it's not a requirement, only a recommendation).
Otherwise, your have the choice for the OS, Plesk is working properly on Centos, Debian or Ubuntu, it's only a matter of choice, depending on your own preferences.