One the things we CAN agree on is the lack of door springs on most Lionel Classic Era passenger cars, with the exception of the larger 300 series passenger cars. Actually one of my pet peeves!
I DO like the American Flyer SG freight cars - definitely more realistic than Lionel's - but I still prefer my Lionel SG Blue Comet and State cars over American Flyer's passenger cars.
Personal preference. 
