mangup, much depends on which programs in which you already have accumulated miles ("orphaned" miles with airlines you don't expect to travel on much in the future aren't as valuable as miles on airlines you do expect to travel on a lot) and in which you might already elite status (for those sometimes significant elite bonuses). Also, Star Alliance and oneworld have been running promotions involving traveling on as many of the partners in each alliance as you can, but not having looked at the fine print myself, I don't know when these promotions expire. So your affiliations are relevant not just individually, but collectively.