I'd prefer to be around Downies. They may not be able to contribute much, if anything to society, but they're usually sweet, open hearted types who don't/can't try to deliberately hurt you or act like an intentional dick.
Autists can be some of the most insufferable people to talk with. If the conversation isn't always on them or their hobbies/interests and you try talking about something in your life, or a different topic, you usually just get a Chris styled "hmm...yeah" and then back to sperging about whatever. Lot of downright rude autists out there as well, and I get the feeling at times a lot of them use the autism card as a get out of jail free to just be a dick without consequence.