I think Forge with prep is greater than Batman with prep, since he can build ANYTHING, where as Batman is limited a bit. He builds a suit that pumps energy into Bishop continously, nuilds a psychic amplifier for Cable to give his abilities a boost, and builds nanobots that shut down cellular proccesses of any cell that doesnt have non-mutant dna.
Batman makes some grenades and talks his team's ear off about how much kung fu he knows. His team gets fed up and leaves.
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"Dunno what your crying for, what did you expect? Im DAN HIBIKI!"
Actually I big debate has already been done about this. Using his ability to understand complex machines Forge can build devices upon the knowledge he posses. He can't biuld anything unless he first has an idea of how the concepts work.
But the reason Forge is so amazing in that field, is well, because he is an inventor. He has massive and extensive knowledge on all things mechanical/electrical/whatever. That's why he's able to do what he does.