During the production of season one of The Best Defense, I did a presentation on the basics of choosing a tactical flashlight, as well as a crash course in defensive tactics using the light as an impact weapon. I'm not sure if it will all make it on the air (we shot a lot more material than the format of the show allows), but if it does, it's a nice primer.
To save you the suspense, in my opinion, a good tactical light for everyday carry should have the following attributes:
• At least a 65-lumen output with a pre-focused beam
• An impact-resistant bulb—either an LED or a shock-isolated incandescent bulb
• Solid, high-quality construction that supports its use as an impact weapon
• Ergonomics that allow a solid grip and effective management of impact shock when used as a striking tool
• A large enough size to grasp firmly with at least a half-inch of the light protruding from each side of your fist
• A small enough size to be conveniently carried
• A pocket clip or carrier that allows an immediate access and draw
• A tail-mounted switch that allows momentary actuation of the light
I personally don't feel that a crenulated or "strike" bezel adds much and, for an everyday carry item, may cause it to be scrutinized as a weapon rather than dismissed as a flashlight.
Beyond these characteristics, a lot of the decision process boils down to personal preference, personal experience with different brands, and your particular level of "geekdom" when it comes to lights.
Mounting a light on a weapon introduces a lot of other considerations. Fuel for further discussion...
Stay safe,
Mike