I can see the advantages of US, but for me, UA tops US providing I can keep my 1K status since that gives me 6 SWUs (= Global Premier Upgrades) rather than US's measly 2 upgrades. Given the amount of Y international travel I do, that's a big difference and very attractive to me. If I have spare miles left over, I may put them in A3 to get United Club access when travelling internally, but given most of my internal travel is on same day as international, then it's hardly worth it. I'll still miss DC though...