I thought my fonts were rendering just fine in Xubuntu, but for whatever reason, I decided to look into my font settings a bit more.
Changing them from default to what you see below (Hinting=full; Sub-pixel order=RGB) has made a nice difference, though. The default font is thinner, but also a lot more readable.
To change your settings, go to the Settings Manager, then Appearance, and then use the font tab.
It takes a minute and you’ll be pleasantly surprised how much nicer your system looks.