Do the people who actually care about this have a phone? Both systems are trash in this regard, but 3DS uses Streetpass which trumps the Vita.
The Vita's Livetweet and Facebook apps aren't too bad in that regards. Does the 3DS have apps for those services? I know it has YouTube, but I'm not sure if it has Facebook/Twitter apps available.
Streetpass > messaging and voice chat.
You are not allowed to request a sticky.