I've tried both and have settled on Xubuntu because it runs faster (particularly on my Netbook) and provides a solid non-Unity experience.
Mint is pretty nice too, but I generally recommend it to people who are new to Linux because it comes with more software out-the-box, looks a bit flashier, and seems to be a bit more familiar to people coming from Windows.
Mint is pretty nice too, but I generally recommend it to people who are new to Linux because it comes with more software out-the-box, looks a bit flashier, and seems to be a bit more familiar to people coming from Windows.