I keep seeing all these people point out champions that give them a hard time and call them OP. Just because a champion is good, or you struggle with said champion does not make them OP.
Overall, the game is really well balanced right now, and it's hard to think of any champions that could really genuinely be considered overpowered. The only one I can think of is Shen. He's banned more than any champion in the game. Overall, he's very strong in lane, and outside of lane too, with his incredibly powerful ultimate. Even at pro tier, Shen is a very frequent ban, and his ability to split push is game-changing. Overall, he doesn't seem to have very many weaknesses while having lots of strengths.