These are what we call the 'YMMV items.' Things that some people find in this work. We call them 'your mileage might vary' because not everyone sees these things in the same way. This starts discussions in the trope lists, a thing we don't want. Please use the discussion page if you'd like to discuss any of these items.
Arc Fatigue: Unfortunately went down this route after sometime, since the arc later separated into several mini-arcs for a while until ending in War of the Supermen.
Complete Monster: Reactron, a Sociopathic Soldier who threatens to rape Supergirl, kills a number of Kryptonians, including her father, tries to murder Mon-El in order to frame Krypton, depowers Supergirl and Flamebird and tries to sexually assault them, and finally blows himself up in the heart of Kandor, killing Supergirl's mother and ninety thousand+ other Kryptonians, gloating the whole time.
Brainiac, who destroys one planet, tries to destroy Earth, kills several thousand Kryptonians, kills Jonathan Kent, and attempts to melt Superman's brain by feeding several world's worth of information into it.
Magnificent Bastard: Luthor is at his best here, cooperating with Lane to achieve a goal he would have worked towards anyway, playing Brainiac and Superman alike to his own ends, and ultimately being rewarded for his role in destroying New Krypton.
Moral Event Horizon: Reactron crosses it in his first appearance, when he kills Supergirl's father while threatening to sexually assault her. General Lane does it when he transforms his daughter Lucy into a superweapon.