I'll go with Iron Man. It's not even close.
His technology is far more advanced. He is far stronger and powerful, with a much higher attack potency and much higher striking strength. He is highly intelligent and strategic, so prep time will go just as well for him as it will for Batman. His multiple beams, such as Repulsor Blasts and the Uni-Beam, will take down Batman with ease.
If speed is equalized, Batman won't easily outmanuvure Iron-Man, and even if speed wasn't equalized, Iron-Man is far faster and that will go well for him. Also he is far more durable, and it would take a lot for Batman to severely damage him. Also, Iron-Man doesn't have as exploitable a weakness as Superman, which also goes against prep time for Batman.
But most importantly, Iron-Man's suit will be able to analyse, learn and counter Batman's fighting moves (which he uses to fight), and therefore outmatch him, like he did with Captain America in Civil War (both the comic and the movie), who is also very well skilled and is in fact even physically stronger than Batman, so he would defeat Batman for the same reason as well as the reasons above.
Therefore Iron-Man will win. Better Technology, stronger, more powerful, equal intelligence and strategy for prep, powerful laser beams, more durable, not as exploitable a weakness as Superman's, and will be able to learn and counter Batman's fighting.
