They're both rich trust fund kids born with a billion dollars at their disposal, but from what I've seen, Batman does a lot more hiring of intelligence/skill than Iron Man. It's clear that he pays others to build/design gadgets for him, whereas Iron Man pretty much does everything himself. The obvious answer is Iron Man IMO. Tony's whole appeal is that he's a cool tech genius with a witty/sarcastic personality who barely does anything physical, whereas Bruce Wayne is this stoic, film-noir detective character who uses his fists 90% of the time.