Iron Man > Batman
Hear me out on this. First of all, neither of them has a super power. The reason they're super heroes is entirely from gadgets that enhance them as humans. And, of course, having the amount of money needed to finance those gadgets. After their parents' untimely deaths,* they both inherit their fathers' businesses and the fortunes that come with them.
*Iron Man's parents die in a car accident, while Batman's parents are murdered in front of him by a mugger.
Eventually they both become super heroes purely from technology alone. This is where the differences begin. Batman decided to fight crime for obvious reasons, wanting to avenge his parents' death. Iron Man more stumbles into it after he's captured by bad guys and must escape without the shrapnel near his heart killing him. Either way, they begin fighting for the greater good for the rest of their lives.
How they get their fancy equipment is what gets me. Tony Stark is a genius, he always has been. He went to MIT when he was only 15 and has a master's degree in electrical engineering and physics for god's sake. Bruce Wayne, on the other hand, is just a traumatized bat fanatic who thinks fighting crime is going to somehow cure him from grieving for his parents for the rest of his life. Sure, he trains himself so he never has to use a gun to take down bad guys, but he needs a bit of help to make sure he's okay when the bad guys do. While Iron Man completely constructs his own suit using help from his robot friend, that he built, Batman uses his endless funds to pay others to make stuff for him so he has more time to brood in his cave.
Aside from that matter, Brucey goes into fighting crime for all the wrong reasons, which is why he's known as the Dark Knight instead of the Well-Adjusted Knight. He spends his whole life depressed and really only hangs out with his butler and a teenager named Dick. Not normal.
Meanwhile Tony Stark is all, "Guys, I can fly". He is way too cool to even have a secret identity and even though he's pretty arrogant, wouldn't you be? He's a rich genius who built himself a miracle suit that's also a huge weapon in case anyone tries to mess with him. Stark is a badass who uses his suit for the greater good because he knows that with great power comes great responsibility and no one had to die to make him realize that, Peter.
Okay, I know they were both members of cool super-groups. But really, who was the coolest in the Justice League and who was the coolest in the Avengers?
I rest my case.