Disclaimer: I've only had to make an emergency fire once, after my son fell into a frozen river on a hike one very bitter windy winter day. We don't have fires very often, and in that instance, we had our canteen stoves and Esbit tabs to cook with. He needed much more warmth than that and he needed it NOW.

I'm a fan of three primary methods of getting a flame or spark, and usually carry all three in the non-summer: I've always got a BIC or mini BIC in a pocket, as well as in my fire kits. There's a ferro rod in all my kits too. I often have it on a lanyard attached to my body or attached to my knife or it's sheath. Storm-proof matches proved their worth to me that day at the creek with my son, when my own frozen finger couldn't work my BIC.

For me, the bigger concern is having dependable tinder, that's ready to go. That day at the creek, all the wood I could find was frozen, and the wind was howling. I needed good sustainable tinder to get that fire started. My fire kits generally contain cotton tampons, jute twine, fatwood, birch bark and a WetFire cube or two. I've always got lip balm in my pocket too, to extend the life of my tinder. I think I used them all that day.

As I foraged for firewood that day, and split branches with my knife to make different sized kindling and fuel, I directed him to take off his wet stuff and put on the back-ups he carries in his pack. After some quick but decent fire prep, I got that fire going, made him some hot chocolate, we roasted marshmallows, ate some cookies, and he and his gear warmed up and dried out. The fire may not have saved his life, but it sure felt like it did. He never made it past the shivering stage of immersion hypothermia and I don't like to think about what would have happened if he didn't.

EDIT RE: Redundancies - I tried to use the BIC in my pocket to light the fire first. Couldn't make it work. Wasn't sure if it was my fingers or the lighter, so I tried my back-up lighter. No go again. By now my fingers were definitely a problem. Grabbed the UCO storm-proof matches and they worked like a charm. In retrospect, my ferro rod probably would have worked, given the tinder I had. I decided against it because I couldn't find my scraper and didn't want to risk cutting my shivering self with my knife.