Just adding an opinion to the fray....

I've flown AA international in coach quite a bit.. I've flown Iberia only once, a coach round trip ORD-MAD and found that I preferred American. The meals on Iberia were not as good as the meals on American (yes, really) and I found the FAs to be rather disinterested/slightly unfriendly.

My Iberia experience wasn't horrible, and the meals/service weren't horribly far below what I'm used to on AA, but they were below AA level. I've avoided Iberia since.