Why not Chakra? Bleeding edge, rolling release, KDE and x64 only. Might wanna give it a shot.
While Chakra works decently out of the box, it is not a 'install it and forget it' OS. Even though I've had Antergos for only a couple of days, I think it's a better fork of Arch than Chakra. For example, I had to struggle a bit to get Ethernet working for my computer while on Chakra while on Antergos it worked fine without any manual configuration. That said, Antergos on my system crashes if the Wifi is N-band
@JCK, if you want a install it and forget it OS, Linux Mint might be your best bet. But if you are willing to put in a bit of effort (not much mind you, a slightly long evening will do the trick) go for a fork of Arch Linux. You can't go wrong with either Chakra or Antergos (Chakra has been around for a bit more time than Antergos). Also, Chakra comes with KDE while Antergos is GNOME. If you have a lot of time, build Arch Linux from scratch

Once you move to Arch-based OSs, Ubuntu based ones look like Windows, i.e, clunky and slow. Arch linux is rolling release so you get the latest update as and when they are released. You don't need to wait for the 6 month release cycle (like Ubuntu) to get new features.