Arch
If unity users are ready to experience a new distro, I'd recommend giving Arch a spin. If Arch is too complicated for them, try the easier derivative Manjaro. Or if they are up for a real challenge and want to experience truly free GNU/Linux, try out the Arch derivative Parabola, my personal favorite. No proprietary software bits at all, including the kernel and the drivers.
I find that a couple weeks with a pure, constantly updated rolling release distro is highly addictive for Linux folks. One of the huge hassles of distros like Ubuntu, Fedora, etc is having to reinstall the whole thing every six months to a year to stay up to date.
Biting the hand that feeds IT
