Heh, not an easy question to answer, at all, at all. Both are excellent settings, and both venture far from the pointy hats of Tolkien ripoffs. Both are more industrial than mediaeval in flavor, and both adress the matters of communication and travel in their own ways.
I do have to agree that Eberron is the easier of the two to convert, though I believe that a start has already been made on converting the Iron Kingdoms. Fantasy Craft would, I think, treat Iron Kingdoms as Industrial, at least as far as tech is concerned, while Eberron uses magic to create much the same result.
Though flavor wise Eberron comes closer to 1930s pulp, a horrific war in recent history, and the next war looming on the horizon. But all done with magic instead of engineering.
The Auld Grump