I've been using almost nothing else than Debian GNU/Linux on i386 and amd64 PCs, since 1992. (I helped birth Linux, and I was part of Debian for a long time.) I have been happy for myself, but speaking more generally, I think it'd be awesome, nay, AWESOME, if computing wasn't so homogeneous. Almost everyone is using Windows or Mac. Outside that, it's mostly Linux, with a few BSD variants. I hope to see that change, some day.

Ideally, radically different, not just another Unix.