I've been watching Les Stroud's "Survivor Man Secrets" and in the fire episode, flares did not work for him. Of course, they were expired ones, but that's probably realistic. Matches get used, ferro rods never go "bad", and if you're a smoker, lighters get used. Flares, not so much.
Of course, I'm separating fire from lighting devices. Flashlights are another topic in my mind. A decent headlight being my top priority followed by another flashlight. Chem lights are for fun or last ditch. The chem light on a rope is a great signalling device, but it's not very bright for working around camp like a head lamp (try it sometime). It's also a one use item (like a flare). I can use a headlamp or flashlight to get a fire going and then turn it off to save the batteries. Once you crack a chem light, you might as well let the kids use them for lightsabers while you figure out how to get out of the mess you're in.