If you don't have specific requirements necessitating another solution (a longer support window, perhaps), I really can't recommend Qubes highly enough. You can run conventional Xen HVMs alongside Qubes AppVMs which 1. are damned fast, 2. can utilize shared templates for disk space efficiency and easier updates, 3. have tools for quickly and securely sharing files or clipboard contents and 4. allow you to intelligently mix and manage color-coded windows in a single task bar. These features are available with Windows 7 as well (Windows 10 is still in development.) Yes, they're stuck using Fedora for the base for now (they'll move to something minimal and more secure down the road) but you can have BSD or arbitrary Linux distro guests and Dom0 doesn't have any network access so there's no reason to be paranoid about it.

The fact that it's probably the most secure full-featured desktop distro ever made (particularly on machines that properly support vt-d) is largely a result of it being a powerful hypervisor. Some people seem to think that it being an ultra-secure OS must mean its crippled or cumbersome but nothing could be further from the truth; it's been a usability win across the board and has been my daily driver for over a year now. I do wish the GUI had better built-in snapshot functionality, but backup functionality works fine and there's nothing preventing you from using btrfs and/or LVM.