I was hoping to hear some opinions from designers here on Free Font. I'm no graphic artist, but I personally always liked the typeface and thought it doesn't get nearly as much love and attention as the other libre/free types out there.
I'm a pretty huge fan of Linux Libertine for serif, although I'm not a fan of the Linux Biolinum. If it had a paired sans-serif that wasn't ugly, it'd be my 100% go to for general purpose documents.