We flew IB J from MAD to JFK earlier in the year, and we found the fully flat seat on IB's A340 was vastly preferable to AA's 767 J seat. It was hard (i.e. not well padded), but flat is flat. I recall that we enjoyed IB's food and AVOD as well, and the service was perfectly satisfactory. The lounges in MAD are probably the same irregardless of which OW metal you fly.