Well, people have preferences. Some people like AoT, some people don't, some like Naruto, some (like me) don't. Some like Kimetsu no Yaiba, some (like me) don't. Some like Marvel movies, some (like me as well XD) don't. But decades of being in the world of writing and film studies makes it easier for me to distinguish which work is done well and which work is not. And like I said, there's no such thing as complete perfection. Flaws will still be there. It's simply about working to make it better.
For example, I gush over Tower of God and Solo Leveling a lot, but they do have a certain flaw (Solo Leveling has a MAJOR flaw despite being amazing). So, while ToG is written pretty well, doesn't mean it's perfect. I'd say One Piece is better.
Good writting is to start a story with a begginning,development and specially a happy ending.
Well, that's your preference, and I respect that. Some people might not prefer flashbacks, and want a straightforward story. Doesn't mean it's good writing though XD Preferences don't have anything to do with good writing unfortunately. Fiction writing isn't as simple as that. And 'good writing' is definitely way more than what most people think it's like.
But anyway, you have your preferences so it's totally fine. Oh, since you mentioned Bleach, I did enjoy the first arc (Soul Society) but after that everything went down the drain. It had potential, but sadly, Tite Kubo couldn't make it happen.