Originally Posted by
zerolife
Number of J seats and quality of IFE depends on the airline and not the aircraft. We really need to know from OP which airlines he/she is comparing.
A318 does exist. It's a smaller version of the A319 and I believe it's flown by several Latin American airlines. I think this rules out AA which does not fly A318.
While the A318 certainly does exist, I don't believe it flies to DFW. Given the OP is considering flying to South America from either MIA or DFW (and is AA plat), AA is the most likely carrier here. I am simply guessing the OP made a typo.
And in the off-chance the OP is in J and could fly a 16 seat 757, that would be far superior as AA has their long-haul J seat on those planes. But, I think OPs usually mention cabin when in J/F.
But you are certainly right that we could provide more accurate information faster if we knew the airline.