My main light is a Quark AA2. My backup is a Maratac AAA. Although it seems like I'm using the Maratac more and more, mainly because I can hold it with my teeth (my lips are like, curled over my teeth, since the sound/feeling of teeth on metal/ice/whatnot is horrifying to me).
If I'm going out with a bunch of people at night or for a long period of time I bring my LD20 along too, which mainly serves as a loaner light/battery carrier.