I started by watching the first three seasons of the anime before I ever read the manga. I decided after watching season four that I wanted to read the manga because I was tired of seeing spoilers on social media. there may be *SPOILERS* ahead.
Overall I love this manga. Once I had caught up to the ending of season four I was starting to get more excited because I had no idea as to what was going to come next. As I started reading more, what would soon become season five, I got more and more into it. Side stories start to become more impacted and characters develop more and more.
Boku no Hero Academia had completed its longest arc to date (Liberation army). As expected from a longer arc more time was devoted to background and side characters. This has led some to drop the manga. I totally understand wanting to just get to the "good" part of the story, I am not a patient person when it comes to wanting to know what happens next. However, I believe that if you could get through some of the dragged-out moments before the big main character scenes it is well worth it.
I wonder if the author has started to write this manga more for the anime rather than just writing the manga to be read as a manga. I am picky about mangas/ books in general that I read because if I feel as though I might start to lose interest in the beginning I will immediately drop the source. But with Boku no Hero Academia I have found that it is worth the wait.