Bernie, because he has a basically zero chance of winning in a general election. His brand of European-style socialism doesn't have much appeal except with on college campuses - the 40% of Democratic primary voters are more or less his ceiling. In contrast, Hillary's brand of crony capitalism seems to sell well enough to people who call themselves "moderates" (at least her husband's pitch of it did), and unlike Bernie, who's considered an eccentric oddity by the RNC, Hillary has the full support of every party machine and super-PAC.
There's an additional reason I'd rather have Bernie as the DNC nominee. He's wrong on just about every issue, but he's not the sleazy crook that Hillary is. I just can't muster the visceral hatred towards him that I have towards Hillary.