I don't really have loyalty to anyone but Marriott, and even then I only manage to re-up my Silver Elite status with actual stays every year. I imagine if I traveled more than I do it'd be a different story.

Typically I fly Southwest for shorter flights and whatever is the least expensive for farther ones. And if I fly internationally I try to use points to get into business class when possible, which UR seems to enable fairly well for me so far.