-interesting characters. JoJo doesnt follow the same characters around, but has a new JoJo in the bloodline. each new JoJo is unique and must face the greater evil or solve the greater mysteries in their own unique way. they are fleshed out characters and you want to see them win.
-wonderful art, interesting artist. Becomes fascinated with high tier modeling and it seeps very hard into his show. character designs become very high fashion and posing becomes frequent. this might not seem like a big deal but it really shows his strengths as an artist to me. what started as a kens rage thing, grew as it's own thing completely.
-keeps things fresh. every 'new book' or season stars a new JoJo in the bloodline. So you get to have a fresh plot every time with a new character, but at the same time it's still JoJo
-''puzzle like'' fights. later episodes become like a puzzle that has to be solved. how can he do this if they do that if he does this and she does that but hes like this.....i think JoJo's greatest strength is it's fights. they get better over time as well, so there's no flat line where it got to it's best and middled out
-unique plots, as barebones as I can explain them in my next reply: