Sanders by a mile. His fans keep posting cheesy memes on Facebook with grandiose pronouncements that mostly amount to the government controlling every aspect of life and informing me I am not permitted to conscientiously object.
I'm not sure I've met someone in real life who will admit to being a Clinton supporter at the moment.
I only see two types of liberals on Facebook: generic Democrats who post Occupy Democrats memes and the Sanders 2016 types. Not many young people seem to be actively backing Clinton.