I don't usually watch shonen stuff, but I like Boku No Hero Academia because it does a lot of things right in my opinion.
I like the story. The plot device of quirks is contrived and not particularly inspired, but who cares. What they do with it is interesting. The characters are interesting and unique, and show real development with time. The show doesn't have a problem with Mary Sues or Gary Stus. The art direction is aesthetically pleasing. The writing has funny dialogue, but can take a serious tone when it needs to. The only thing I don't really like is how much the characters (mainly Midoriya) cry. It was alright in the beginning, but it should have been scaled back more as the series progressed.
It does feel like most of season 2 and season 3 has been kind of stagnant, but honestly that's kind of what high school is like compared to real life, and they work with that hangup pretty well by making the lessons, exams, and exhibition aspects of real life high school flashy and interesting by making it about super-human feats.
I get why this show wouldn't interest a lot of people, but for what it is and what it tries to do, I think it's exceptional. People that hate the show probably just don't like shonen stuff or superhero stuff. That's fine, but they should spend more time watching anime they actually like instead of shitting all over BnHA threads on /a/.