what's the best operating system?
I have 3 licenses for the Windows, W7 W8.1 and W10,
which should i choose?
i havent decided which season i will run
None of this versions is suitable for 24/7 up-time. As Mr X told you, use one of the "Server" version - for older files you can use Windows Server 2003, for S4 and newer I can recommend you Windows Server 2008 R2 and for S8 and newer Windows Server 2012 R2.