Not defending AA at all, but it is way better that UA as far as limiting when it offers TOD upgrades. Also, go check out the UA forum for how many 1K's are disgruntled about their lack of upgrades. And good luck purchasing the expensive Y fares that DL makes you purchase to apply a SWU with them, only to be upgraded to an older, often inferior hard-product of their business class. Each airline has their issues and none are perfect among the big 3 in the US.