I was about to leave Star Alliance behind, but I'm about to get booked on a rather lengthy J itinerary, so I should probably revisit this.

(1) Home airport: MCI
(2) My normal fares in *A have historically been discount-Y, but I'm about to embark on a journey of about 12,000 miles on UA and Avianca in a mix of J-type fares. Could include D, Z, and P.
(3) If I brought my Oneworld and non-alliance travel back to Star, it'd be 20k-25k/yr.
(4) Current status is Star Silver thanks to A3. I will have no A3 metal in my travels anytime soon, so I've pretty much given up on pursuing status with them in the future.
(5) Most important, in this case: lounge access and other minor perks on United. Since UA Silver so rarely gets upgraded, I would value partner Star Gold over native Silver.
(6) Aside from domestic U.S., more Europe than anything. Although South America (in C/J) could pop up 1x-2x per year for a while.
(7) No particular preferred airlines.
(8) Do you travel for work or pleasure? Both. Pleasure tends to be discount-Y or award travel though. Biz would include some medium- and medium-high coach fares within the U.S.

Thinking Asiana based on first review of the various options...

EDIT: I have booked the aforementioned trip. U.S. to Lima on United in P. LIM to EZE on Avianca in D, EZE back to the U.S. on United in Z.