"This is one of the biggest FT misconceptions. DL, NW, and CO have almost all the same partners, so mileage redemption is virtually identical between all 3 programs."

Sorry to disagree, but there are some major differences between CO and NW (I can't comment on DL). It all depends on how you want to use your miles. Want to fly QF to Australia(Only CO has an arrangement). Want to fly MH to Asia (choose NW). Want to fly Air Tahiti Nui to Tahiti, only NW once again.