It's hard to pinpoint a single 'strongest stand' in Jojo manga. Different stands have unique abilities and advantages. For example, The World has the power to stop time, which gives it a significant edge in many situations.
A great concept for a 'jojo persona crossover fanfiction' would be a tournament - style story. Characters from both universes are forced to participate in a battle royale. The Jojo characters would bring their Stands, and the Persona characters would have their Personas. The battles could be intense, with different strategies emerging. For instance, a Persona user might try to use psychological attacks against a Jojo character who is more used to physical combat with their Stand. And the story could also explore how the two groups of characters interact and form alliances outside of the battles.
One idea could be to have characters from 'Game of Thrones' possess Stands like in 'Jojo's Bizarre Adventure'. For example, Jon Snow could have a Stand that gives him enhanced combat skills in the cold, similar to his natural ability in the North. Another could be a story where Daenerys' dragons are somehow related to Stands, perhaps her dragons are manifestations of a powerful Stand she unknowingly has.
One idea could be to have the Stand users from JoJo interact with the Personas in a battle royale - style scenario. Maybe the JoJo characters are transported to the Persona universe and have to figure out how to use their Stands alongside the Personas to defeat a common enemy.
One idea could be to have the Jojo characters enter a popular video game world like Minecraft. They could use their stands to build amazing structures or fight off mobs in unique ways. For example, Star Platinum could be used to mine blocks at super - fast speed.
Maybe a story where Steven, being his empathetic self, tries to understand the complex and often morally grey world of JoJo. He could meet Jotaro and learn about Stands. In turn, Jotaro could be intrigued by the Gems and their unique way of life. This could lead to a series of adventures as they try to find common ground between their two very different worlds.
A cool plot could be a time - travel story. What if Jotaro Kujo somehow ended up in the Naruto universe? He could use his Star Platinum to take on some of the powerful ninja there. Or perhaps Naruto travels to the Jojo universe and has to learn how to use Stands. He might befriend some of the Jojo characters and together they face off against the enemies in that world. Maybe Dio Brando discovers the power of chakra and tries to use it to enhance his vampire abilities, which would draw the attention of the Naruto characters who would then try to stop him.
There's no way to really tell if it's common specifically for someone named Jojo. However, in general, reading fanfiction is a popular activity among fans of many different franchises. The Jojo series has a large and dedicated fan base, so it's likely that there are fans named Jojo who partake in reading fanfiction, but we can't say for sure how common it is without more data.
Well, for 'jojo's bizarre adventure crossover fanfiction', a crossover with 'One Piece' could be great. Picture the Straw Hat Pirates meeting the Joestar family. They could have adventures together on the Grand Line and in the JoJo universe. Also, a crossover with 'Naruto' would be interesting. Ninja techniques and Stands could clash or work together. And how about a crossover with 'Bleach'? Soul Reapers and Stand users could face off against powerful Hollows and villains from the JoJo world.