Age of Ultron is a remake of the 1st Avengers movie except for bigger plot holes, an unnecessary romance subplot that's out of left field between Black Widow and Hulk, an another unnecessary subplot by the least interesting Avenger, Hawkeye, a horribly ruined interpretation of Ultron that easily kept getting his ass whupped, and another cliche 3rd that you seen before in Avengers, IM3, Thor 2, Winter Soldier, and Guardians of the Galaxy (minus the dance off and holding hands shyt). It had terrible CGI, awkward pacing, and felt more like a FILLER episode rather than a tent-pole event.
Batman v. Superman is a continuation of Man of Steel but is rather choppy in its editing (which can be faulted for it not being the true full version of the film), have a controversial and mostly negative take on ALEXANDER LUTHOR (must remind people that he's not the OG Lex) and it is because Snyder made this choice is part of the controversy. An illogical rationale for introducing Doomsday and forcing Lois to be one of the focal motivations being ill-advised. Also it had an ineffective reasoning for Superman wanting to fight Batman. That all said, it is the BETTER film than Age of Ultron with the potential of being an extremely DOPE film once the Ultimate Cut gets release because only then you see everything in full context as Snyder intended and if anyone of us has learned from Watchmen, the Director's Cut is way far superior in every way then the theatrical cut. Plus, the warehouse fight is one of the most mesmerizing fights scene in comic book movie history OR AT THE VERY LEAST the greatest ever in any Batman film. Also, Wonder Woman did much enough to get hype for her solo film, especially with the Doomsday fight. Lastly there's so much to digest in introducing the DCEU that no matter what, you cannot discuss theories and ideas of what could happen next. So, flaws and all, BvS is the more enjoyable film.