Now that a decent number of games that I play have native Linux clients thanks to SteamOS, I have no reason at all to switch back to Windows. The Civ games, EU4/CK2/Cities: Skyline/Mount and Blade/all other Paradox titles, the Football Manager series and many others all run natively on Linux and they are the bulk of the game playing that I do.
The programming tools are better, I prefer command line for system maintenance than searching around an increasingly thickened Control Panel with confusing descriptions, and maintenance of Bluemoon's servers and DB is much, much easier. Also in development terms as the server also runs on a Linux variant, just having a proper local testbed setup rather than using a remote one saves an awful lot of time.
Not a fan of Ubuntu as GNOME is ugly as fuck but Kubuntu uses KDE/Plasma and is lovely.
I was into Windows 10 during the beta but found quite a few compatability problems with older programs (Football Manager 2012 will just patently not run on it at all for example whereas it runs perfectly under WINE), and I'm not a big fan of the privacy violating options that are controversial. It's an excellent operating system for the use case of just wanting a computer to work properly without much pissing about, and the interface is a million times better than previous versions but it's not for me personally.