I'm not sold on this at all. Avengers 2 will be the biggest film of 2015, sorry, not Superman vs Batman (or whatever it is being called). As popular as Superman is, RDJ has taken the GA and transformed Iron Man in being the biggest 'must see' character in the last few years. People are more pumped for Iron Man right now (specifically saying right now, not in general since superman in general I think is more well known and loved) and any movie vs superman or batman.
A lot of the talk surrounding superman vs batman is a lot of hate towards Affleck being batman, not so much positive news. We'll get a better feel for this when the first trailer comes around. Right now, you have to go with Avengers 2, hands down. It's not even a contest.