Gentoo Linux / Windows 8 Pro in dual-boot, I've used Windows since I was little so I kind of grew up with that. I wouldn't say one OS is better than the other because this is something subjective.
The one and only reason I still run Windows is gaming, although I've managed to get the Steam client for Linux to work and even played some rounds of good ol Counter-strike 1.6.
I'm mostly on Gentoo because I like to be able to tweak every nut and bolt, this particular distro has a big learning curve and just installing it can take days with several attempts.
An interesting viddy about how Linux is built;