Two major ones:
King Sombra. Guys, he did wxacy what he was supposed to do. We weren't supposed to know too much about him. An extensive back story wouldn't have been necessary. King Sombra himself wasn't the antagonist, it was the threat of his return that we should have been worried about.
And now for the big one. SUPERMAN. I love the Man of Steel, and it pains me when I see all of the usual criticisms against him. "He's overpowered", "Mary Sue", "bland and boring". And I'm just sitting there like, "no, youre wrong!". Superman is and incredible character with tons of emotional depth and internal flaws, but people instead only look at how harf he can punch or how much he can lift. Seriously folks, pick up a comic book, rewatch Man of Steel, just please, do something so that you can form your own opinions instead of listening to the ill informed opinions of others. My biggest hope for Batman v. Superman is that it finally changes the general public's view on Superman.