People who have a bit more than just half of a brain. (One of my biggest pet peeves is reading what someone has to say and wishing that I could inject spell-check into their page.)
It's always easiest to put out what you're not looking for than the redeeming qualities of a person since there are so many and multitudes of combinations.
You have to be easy going, possess your own opinions, and be willing to stand up for what you believe in. I generally tend not to be very tolerant of ignorance, bias, or judgmental people.