Pro or enterprise version of windows will be plenty fine, enterprise just provides more security, virtual machine software, and IT control over more computers over a network if that's what you want - though it's overkill for a simple gaming rig and won't really provide more performance but possibly less bloatware. Though pro version itself doesn't really come with bloatware at all either, usually you find pre-installed bloatware software on pre-builts or laptops. If you're installing Windows yourself it should be fine and mostly bloatware free (a few windows apps may weasel their way in, nothing major though).