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I'm very partial to CentOS 6 myself because it works in both server and desktop situations due to its 10 years worth of updates and the use of GNOME 2 (and ye olde but easier to admin Sys V init scripts). Hence, it's my primary Linux desktop and it's on most of the Linux servers at work too.
And if it gets a bit too "creaky" after several years of service, they'll always be the option to move to CentOS 7 at some point (though the beauty of CentOS 6 is that you'll get updates even after the releases of CentOS 7, 8 and 9!).
If you're coming from XP and want something that gets updates for ages so you don't have to do any major upgrades, CentOS (or RHEL) is surely the best choice?