I think Gentoo would be a bit complex.
I second a Debian or Ubuntu-based distro, but not with the Unity DE. Unity has some controversies over privacy; sending keystrokes to Amazon, etc.
My personal favorite is KDE; it's very modern, has lots of features, yet, it gets the job done. For lighter-weight systems with less resources and power, Xfce is also a good choice.
But, there are many options to choose from.