I've found if you have eye shades and don't choose a seat by the galley, AA is actually better for shut-eye out of MIA - ask for the Express Meal and it will come very quickly and then you can rest; and they ask whether you want to be woken for breakfast or not (NO!)...
I'd take AA if it's the 777-300 you;'re talking about here - especially if you can get Row 3 in the mini-cabin