Well, here at Chateau Sinister we have various systems running Linux (Ubuntu), XP, Vista, Win7, and Win8 on the home network, and some iPad and Android tablets too, so I think I've probably seen everything worth talking about. My take on it is that Linux is the best operating system from a design perspective, it's smart, fast, easy to secure and control, and has all the productivity apps (free!) anyone could ever want. The only knocks against it are that it won't play the Windows games and it's a little behind the curve on driver development for the most modern hardware. And Android is Linux based, so it's better than the systems on iPads and iPhones, you can actually find out what it's doing and make it stop, if you're so inclined. And I am, I don't want a device to be online all the time and be unable to find out or control what it's doing out there.
XP I think is the best of the Microsoft offerings, Vista's a pig, Win7 is no better and has a frustrating and infuriating security system it shares with Win8, Win8 is smaller and faster than either Vista or Win7 but its default tiled interface, what everybody but Microsoft calls Metro and Microsoft calls the Start screen, is nothing but a nuisance on a non-touch screen, and if you have a large monitor the touch feature is inconvenient, the screen's too far away to use that feature conveniently. I've never liked touch screens much anyway, they rapidly get fouled with fingerprints, have to clean them far too often. Support for XP will probably be ending within a year or so, and you really shouldn't run with an unsupported operating system, so you'll have to migrate to Win7 or 8 at some point, XP and Vista are no longer available as far as I know. My advice would be, if you're running Linux you don't need any advice from me, if you're running XP or Vista go to Win7, if you're running Win7 and it's working alright for you stay with it, don't go to Win8, if your hardware is slow with Win7 go to Win8 and install the Classic Shell, and if you acquire a new system with Win8 do the same, install the Classic Shell.