Joseph is best Jojo. I think this is just internet fact by now. (If not, it should be.) While all Jojos have something wonderful about them, something about Joseph is just decidedly excellent. He is the Original Pranksta of JoJo's Bizarre adventure and honestly, I think he is a lot of what really pushed me into continuing the series early on. (Don't get me wrong... I loved Part 1, but I really really fell in love when I read Part 2 and Joseph definitely played a big part in that.) I feel like Joseph is not someone that can really be described in words, so here are a few images I think represent who he is as a person far better than any TL;DR I could spout.
Unlike his goody-two-shoes predecessor Jonathan, Joseph is lowkey one of the biggest handfuls in an otherwise honorable line of Joestars. Brash, loud, and extremely hot headed, he lovers to play pranks, spy on girls while they're bathing, and will willingly run from a fight if it means it's the easy way out. He's drop dead gorgeous and he knows it (probably also one of the only womanizers in the Joestar family) and despite being rather lazy, will never back down from someone who challenges him. Far removed from his gentlemanly grandfather, Joseph plays the role of comedic hero throughout Part 2. He very rarely takes things seriously (much to the dismay of almost everyone around him). This doesn't sell Joseph very well and in all honesty, there's very little redeeming qualities about him: but Joseph wholeheartedly embraces the fact that he is a cocky jerk, which is weirdly what makes him so lovable. Fans don't love Joseph because he is good and pure. Fans love Joseph because he a pranking, cross-dressing, self-absorbed (but otherwise well meaning!!) asshole.
"He-llo? Could you say that again? More slowly? In a language I understand? Depending on what you said, I might kick your ass!"
On the flip side (and a more positive note): Joseph is an incredibly powerful ally and an even greater friend to those fortunate enough to call him one. Because of his love for playing pranks and being a little shit, he has a knack for being able to outwit the enemy by playing mind games and tricks on them. (That is to say, Joseph finds no shame in playing dirty.) The combination of his brute strength, hamon abilities and sharp wit make him a deadly combination to deal with. Joseph is really wonderfully written in the way he manipulates his enemies: he is the type that loves to show off, so battles are never dull if Joseph has taken the stage.
And while Joseph has always left me starry eyed with his showmanship, it's his surprisingly big heart that really won me over in the end. Though he loves to goof around and be the center of attention, when it comes down to it he cares very deeply for his comrades and would do anything to protect what is important to him, just like any other Jojo protagonist. Fans of Joseph are quite fortunate in that we get to watch him grow old with the series—something that doesn't happen often, even in long running anime. Joseph is around for about three arcs, starring as the main character in Part 2, and lesser roles in part 3 and 4, where he eventually becomes the cutest senile ol' Grandpa in anime history. And as he grows older, he does mellow out quite a bit, but his good heart doesn't change. He's always willing to put his life on the line for those who need his help, even as an old man. (He also may or may not adorably spend thousands of yen on diapers for an invisible baby... just sayin', old Joseph is just as if not even more cute than young Joseph.)