I currently use Windows 7, and have done continuously since the release candidate, and generally find it to be excellent. Nonetheless, I'm trying to make a concerted effort to switch to Linux; mostly to support FOSS, but also for a few practical considerations.
Having played around with a number of distributions in VirtualBox, I've come down to a shortlist of three: Kubuntu, Linux Mint and Fedora. I very much like KDE, mainly due to its reasonably traditional but still innovative shell and its excellent handling of window snapping (it's just what Aero Snap should have been!), so even if I go for Linux Mint or Fedora I would use the KDE versions.
I'm reasonably comfortable with Linux, having used Fedora in the labs at university, and used Ubuntu/Xubuntu in a VM whenever I needed access to Linux at home.
My question is, why should I go with Linux Mint over Kubuntu or Fedora? Most of the comparisons I find on the internet are essentially KDE vs Cinnamon vs GNOME vs Unity etc. rather than the actual OS, and as I'd go with KDE whichever OS, those comparisons don't really apply.