Just a few points for those who are sad about losing their place in *A for an entrance to 1W follow below.
1. *A has a great network in theory, but trying to redeem J or F on SQ isn't child's play. Air New Zealand is a fine airline, and the food on ANA is excellent, and the coverage for Europe from the LH group is outstanding, but the UA/CO mess isn't solved by a longshot, and the repercussions not yet fully understood. Plus, SAS!
2. 1W has fewer airline partners, but the quality of said partners is rather more consistent. CX service on the ground and in the air is excellent, and BA, Finnair, JL, LAN, IB, and Qantas all have generally positive outcomes (with some exceptions that prove the rule that we expect them to do well by their passengers). 50% of the 1W airlines are 5-star airlines per SkyTraxx, if that has any value to you, far superior to the other alliances. I also have good expectations for Malaysia and Air Berlin for the future. In addition, you have a slightly better set of Alaska Airlines and WestJet perks than before.
3. Just think - at least you aren't going to deal with SkyTeam, the grab bag of the air leftovers! Alitalia! Areoflot! The rump of Northworst! China Eastern! Garuda! Hooray!