I fly enough segments each year to quality as an AA EXP and a UA 1K. Since award redemption is critical to me, Delta is a non-starter. Both AA and UA have plus and minuses, and neither is so bad to cause me to walk away and neither is good enough to win all my business. So I keep flying both until one wins all my business or loses it. And I'm especially interested in keeping my 1K status as I evaluate the US-AA merger.