Steel ball run is the the perfect JoJo part and the part where Araki truly perfects his classic format of meeting stand users throughout parts of their journey. He perfects this through my favorite JoJo plot by far, the steel ball run race which is an amazing setting for this format and the adventure genre that takes the best features of every other part and puts it into one masterpiece. Along with the amazing plot and format, this part easily has the most depth when it comes to character designs and had me in love with everyone from Johnny to Lucy Steel etc.
You can tell Araki really wanted the main characters to have has much depth as possible and did this by giving some great backstories and amazing development. I really loved this because I feel that one thing that many parts lacked was depth and well thought out backstories that drove the plot and in this part he really changed that. Regarding the depth and backstories you cannot overlook in my opinion the best antagonist in all of JoJo and one of my favorites in all of manga and that is Funny Valentine. Funny Valentine is a truly unique character in the universe with his amazing analogy of "picking the napkin up first" and the incredible way this drives his motives of true patriotism and protecting his country.
Next there's Johnny who is arguably the best written main protagonist in the series who I feel is up there in readability along with characters like Josuke where we can really see his weakness and the struggle he faces in the beginning that he's forced to overcome and drives his development. This is one thing I thought was lacking in other parts like two and three where I felt like the main JoJo's had little development throughout their parts but I was glad to see Araki execute this is well in Johnny. Following Johnny lest talk about Gyro Zeppeli who is one of the most enjoyable and well written Jo-bros. As we meet Gyro from the beginning its clear that he will be one of the driving forces in the series and contributed to Johnny's development more than anyone else. Finally it wouldn't be a proper review of the manga without going over its art which is a true display of Araki's amazing talent and how much he's improved his art style with every single part. Araki manages to change and improve his art style so much and still have such recognizable and incredible art. While I don't consider it the best art in manga, Araki's style in this part is one of my personal favorites and really adds to the charm of the series. Overall Steel Ball Run is a masterpiece of a manga which excels in its art, themes, characters and plot making it my personal favorite manga of all time and a contender for best manga of all time. I highly suggest to both JoJo fans and non JoJo fans alike.