mine would have to be either stands or araki's love of fashion. i think stands are a great power system that allow for so much creativity in fights, and i love spotting the easter eggs araki throws our way. also, the character design is iconic, even if it doesn't always look good. you can always tell that a jojo character is from jojo
easily the best character designs in manga, i have no clue how araki comes up with this shit but it works

here are some things i've gathered from the interviews he's done:
i only found these things out very recently, but i think these are the key to unlocking how araki creates such unique designs
that roman sculpture one is such a good point, i would have never guessed it but it makes so much sense lol
araki is seriously a master at his craft
although it's greek, he specifically mentioned discobolos of myron as a great example for what he looks for in posing. i don't remember what he said exactly, but araki mentioned something like "the statue cuts all the excess parts out" or something like that. i think what he means is that the pose is clear, has a good line of action, and is easy to tell what's going on

this took me like 10 minutes to figure out how to use gifs in anilist
sorry i don't think it's working, could you paste the link?
sad it's not working https://i.imgur.com/OlRxFsk.mp4
How expansive it is: covering multiple generations, locations, alternating casts, references to music, fashion, cuisine, culture, etc. When it comes strictly to story and characters there are plenty of other series I prefer tbh, but what I love about Jojo is how unique an experience it is and the unbridled creativity/chaos that it oozes.