My recommendation is AA's Advantage program. I was in the same boat as most of my flown miles are on QF, but the ability to provide miles to my wife and married daughter in the US has been most important. There have been a few times when family situations (one birth and one death) presented a need to be on the next plane out. In both situations the awards were immediately made for the next flight with no fees to expedite the award. That's worth a lot to me.

When hitting Executive Plat you also get very special care and it will probably be hard to go back to UA if you get spoiled like I have been. The real secret is to get only one for miles accumulation - when you hit the million mile marks you make lifetime Gold (1 million) and Platinum (2 million).