Monsters University is the better overall movie, in terms of plot, depth, characters, and the superbly detailed environment.  However, Despicable Me 2 wins the single most critical aspect – funny.  Despicable Me 2 is simply many times funnier than Monsters University, because the former spent a huge amount of screen time to the jokes rather than the plot.  For an animated movie, being funny outweighs everything else.  There may be people who do not appreciate the minions and therefore do not think they are funny, but the box office has already proven them to be a minority.  I predict Despicable Me 2 will win the box office at the end.