hands on is always good but if you are looking to use that information to get a job you need to get certified in it. VMWare is the market leader right now but Virtuozzo also has a very good product. look into getting certified in VMWare but try to get some experience in the number 2 just in case your prospective employer uses the product.
you will also need to get a lot of experience in either windows server or linux to be able to use that vmware cert. if all you know is VM and can’t backup the server OS’s that are running on it then your cert will be useless.