UA actually has some weak points that no one touches on, the biggest for me is the overpriced cost of some non-USA starting routes. In some of these instances a US vs UA redemption can have a difference of almost 50%, like what I a recent redemption EU-Asia I had.
That being said, I am furious about the fact that I can't burn Skygarbage from Europe going to Africa or Asia without paying a crazy fee. My girlfriend is there and I wanted to use the miles to go somewhere nice. At that point it's basically the same price for me to buy her a ticket to the US and just leave from the US with a stopover.
I think this is just biased, and the groups with the most members will always win, a la Freddie Awards. Why is US so far down when they have the lowest redemption rates and basically the same availability as UA is confusing as well - oh, wait...no one here uses US miles.