Spider-man has always appealed to me, because despite his super powers, Peter Parker's life kinda sucks. He's constantly juggling jobs, relationships, and other real life responsibilities, along with super villains making his life miserable. Spider-man also has quite a lot of antagonists that know his real identity, which must suck!
Being Spider-man is not easy. He has to sacrifice a lot to protect people, and then gets blamed for it in the newspaper. He can't form a relationship with anyone, without putting them in peril. His work is a terrible thankless one, and that makes him likeable. I like seeing characters be put through the wringer like that.
That is not to say that Superman has an easy life. But at least people appreciate his heroics. In comparison, I find Superman a bit bland and boring. For me, a compelling superhero is one with an interesting unique power, a struggle to keep their identity a secret, weaknesses, and a lot of hardship. Superman's only weakness seems to be one invented for the comic, and it seems like he has ALL of the powers. Not very compelling.
Batman is more relatable, although his vast fortune clearly is not. But what I like about him, is that in the end he is a vulnerable human being. He relies not on super powers, but on gadgets, martial arts, and detective work. His villains therefor don't need to rely on super powers either, and this adds a thin layer of realism to his adventures. Sure, 'some' of Batman's villains have super powers, but his best antagonists don't. They are 'normal' human beings, with a quirk that counters one of Batman's weaknesses. And to me, it is especially this last detail that makes his adventures intriguing.