I was originally introduced to JJBA through a really good friend of mine who loved the series, and inspired me to take a shot at getting into it. My initial thoughts prior to actually watching the anime was that I didn't think it was a show I'd personally like, though I'd seen countless internet memes and posts from fans of the show before. I believe it was around 2018 when I decided to start Phantom Blood, the first season, and unfortunately I had the same sentiments as most newcomers to the show have, which is that the first part is sort of hard to follow along with. I had watched maybe 3 episodes before inevitably forgetting to continue and let it sit in my Netflix watch history for a good month or two before trying to get back into it and somehow, I was hooked.
After retrying to watch along, suddenly I could not stop watching, going from Phantom Blood to Stardust Crusaders immediately, and that's when I really started to fall in love with the show. From then on, I'd continue through the series, leading all the way up to the last released part, Golden Wind, and soon enough; I had finished catching up to the anime completely.
Looking back now as a dedicated fan, part one of the series has a mixed reaction, with some adoring it and some finding it the worst of the series, but I don't think I'm in either crowd. While it was harder for me to get into originally, I think it was more-so my predisposed feelings towards the show that made me apprehensive to getting into it, as now I find Phantom Blood nostalgic and a great start to the story.
Currently, I have yet to finish the manga counterpart, my last bookmark being with the start of Part 8: Steel Ball Run. With this shrine, I think it's re-inspired the feelings I have for the series, so I think I'll pick back up on it so I can stop avoiding spoilers like the plague.
To finally answer the question, I think I love JJBA because despite the story changing between each part, I never find it hard or difficult to get attached to any of the new characters, whether they're a side character or main. It's reminiscent of how Final Fantasy operates, where each game is an entirely new story-line, and if one game isn't as optimal, there's other games with new characters and aesthetics. However, the only difference is that while you can just pick any game in the Final Fantasy lineup, I don't think the same tactic can be used on JJBA. While yes, you could just start anywhere you'd like, I think following the story linearly lets you follow along with the Joestar generation, and it makes each part much more impactful.
Something else that I find this series so endearing is Araki's art-style evolution between the parts, which is typically acknowledged among both fans and outsiders. I've always been in awe of Araki's ability to create fluid poses without so much emphasis on anatomical correctness but not to where it looks wrong. It helped me with my own art to realize how rapidly styles can change, while still holding some elements of previous renditions. Araki's character designing is something I admire, as well as envy, because they're incredibly memorable and mostly unique, each Jojo having their own aesthetic to match their surroundings. I can only dream to create characters as imaginative as Araki!