I have to admit when it comes to marvel universe I'll take it over D.C or transformers simply because it's more believable that there's an undiscovered powerful element out there. Plus lets face it we meet people who act like Iron Man in our world and not really like a robot vehicle.
FYI, marvel created transformers. They even were in the normal "Earth-616" universe. They fought megatron with ironman. But, as far as i know, marvel sold the complete rights to use the transformers to someone else. So now the transformers comics are set in the same universe as G.I. joe now. I like both transformers and iron man. However, if you say "Who would win in a fight, transformers or iron man?" It depends, Do you mean one transformer? If so, which one? Do you mean all of them? Then, obviously a entire species could easily beat a single powered man. Do you mean only the autobots or decepticons? Well, still, advantage of numbers. Rereading this paragraph, it seems like im kind of acting superior for pointing out knowledge anyone can find on wikipedia or another wiki. Im sorry if it is that case, and this block of text has upset you or made you feel uncomfortable in any way.