i switched to ua for my primary international flying a few years ago and i'm very pleased with the decision and haven't looked back since. although i mostly fly out of a nw hub and flying ua means an extra connection half the time, having various upgrade instruments that one can actually use perpetually available and access to E+ are two of the tangible benefit differences.

at one point, wp was the best program for domestic flyers (it still may be, marginally) mainly due to unlimited upgrades. of course, on certain routes and flights it is almost impossible. with significant lessening of the elite membership value lately, i have less of an incentive to fly the no-longer-a-hometown airline.
i "jumped ship" (although i still fly enough on a higher-tier fares to maintain a PE status) when they were at the height of nickel-n-diming us to death (initial intro. of coachchoice or whatever the heck they called 'premiuim seats for more $$' was the straw that broke the camels back for me).

thanks to the carryover MQM policy, i'll probably just end up maintaining a mid-tier status just to avoid baggage fees when i have to fly on dl.