This debate has been going on since superheroes first came to be. Most superhero fans, though, will agree that super speed (like the Flash) is the number one power. A person who can run so fast that he can't be seen is virtually unstoppable. The possibilities for someone so fast he can't be stopped are almost endless.
i think spiderweb is the best superhero power because you can grab enimies with your web and punch them or you can swing them around or you can do a superspin slam with it and you can swing and launch your self in action with a super kick
The best super power would have to be telepathy. If you can read and control people's thoughts, there really is no limit to what you can accomplish. Of course, this also makes for a really powerful villian.
My favourite is superman. Because importantly he can fly, and the x-ray vision to see things through, and the power to lift huge weight and the power to stop anything which will harm. And importantly he can run faster and faster than anything.