Even if it's usually labeled as that, Ashita no Joe it's not the best option for boxing fans, but for people who appreciate a great storytelling, characters and drama. If you are looking for the best approach to boxing as a sport there is nothing close to Hajime no Ippo.

Some people say it gets boring or is too long, but in fact there is not a single moment when you think you are reading filler chapters, Hajime no Ippo is like following boxing in real life for a decade or so, new fighters arise, others decline, etc. With Hajime no Ippo even if there is a main character (Ippo) this is not just his story, but the story of boxing during the years of his career. There you have many weight classes, different boxing styles and the personal life of each one of those boxers.

That's why this series is so long (1311 chapters as I write this review), because usually any pro boxer will have around 30 to 60 fights in his career. You can't rush things, this is not a narrative created by Morikawa, but a translation of a reality to a manga, the perfect portray of that reality (as luckily happens with HnI) needs to be this long, each one of these characters needs to evolve, to train, to change in their weight classes, be the best in their countries to go for the world fights; it's not about repetitive storytelling, it's just about how this reality works.
That's why for me right now this manga it's probably at the best moment of the entire series, because many of the characters are approaching or are already in the elite fights, if you think it's dragging too much maybe the problem is that you really don't appreciate this sport, and you are looking for just another story where this is only about a main character who gets bullied and the story ends when he gets his Japan belt and marries the girl he likes.

George Morikawa makes clear his love for boxing and knowledge about it (he is involved with it in real life as the owner of JB Sports Gym in Japan and is the manager of the boxer Manabu Fukushima), many of the fighters and situations come from real life and boxing history. This manga introduces boxing techniques, styles and develops fights with a much greater depth than any other manga related to this sport. That doesn't mean that there aren't things that could be better, as an example to be more mature from a narrative point of view with its typical shonen approach to romance, etc. As drawing you couldn't ask for much more, it's really good as it is thinking this is a weekly series and one of the longest ever.

If you share that passion for this sport Hajime no Ippo is the way to go, if you are looking for a great and moving story maybe Ashita no Joe is a better option.