These are the main reasons for me:
1.) The author has no motivation to make the story logical. Even if you put magic in there, at least make sure it has sense as to what it's strong to or weak to as well as why it's better than the other element at certain situations.
2.) World building sucks. The world building is very important. If you're going for like an ancient setting or a medieval, stick to it. Unlike Naruto where they use a huge amount of chakra to send a message, then in the next few scenes, they use radios.
3.) Unrealistic Characters. Your characters should have flaws, they shouldn't be perfect. They should also be interesting and, in my opinion, human-like. What I like to do is I pretend to be that character. If I was him/her in this situation, what would they do? Something like that.
4.) Bad Grammar. I for one, am not too bothered by grammar, but if it's the Grammar inquisition, they'll gun you down. Word of warning.
5.) No Direction. Make sure that the story actually has a main goal, and make sure it's actually good. For example, Attack on titan. I won't spoil though, just saying.
6.) No/messed up power system. When making a character or a monster, make sure they have a power system. An example of a bad power system is seven deadly sins. Mc's weak, he gets powered up, he beats the enemy up EZ Peezy. That's bad. An example of a good power system is HunterxHunter.
7.) No stakes. This is connected to number 6, there needs to be a sacrifice or something. It can't be called a good battle if the good guys one-sidedly win. Well, I'm not saying death is good, but like in number 1, be logical.
8.) The author has no motivation at all to listen to the things I've given.
Well, these are just my opinions, but it's your story, it's your choice.