>>625584sevens and Fenix are very good choices. SureFire is reputable, but their stuff is overpriced.
Personally I carry a discontinued Nitecore D10 because of it's simplicity, twist/switch/momentary on/off, and fluid variable brightness. Things I look for in a light are the following:
-1xAA battery, AA batteries are common and plentiful as hell, and it only needs one of those fuckers to operate. Sure, CR123's are much better, but they also cost more and they're not as common as a simple AA. Need one in a pinch? Steal one from a TV remote.
-Being able to tailstand/use as a candle. Put a diffuser on it and you'll be able to use it handsfree.
-Variable brightness settings. Brighter does not always mean better. In some cases full brightness setting will end up blinding you when you work in small confined spaces, or when trying to look into small parts. Being able to set it on low or medium will give you enough light for those situations.
