I use the four D cell Maglight as a reasonable compromise between convenience and use as a weapon for in the vehicle. My father, (a retired police officer) once hit a guy in the side of the head with one & the "perpetrator" went straight down to the ground. They even have a book of tactics for the use of the flashlight for personal defense.
I use a Surefire 9Z when I want a bright light. Just be advised that the batteries die suddenly without warning. When the voltage drops below that required to light the xenon lamp, it goes from very bright to very dark instantly. Be sure to carry extra batteries. The CR123 batteries are reasonably priced at Surefire's website but about $8 each at the drugstore. I edc a minimag with a piece of Tygon tubing on it so I can hold it in my mouth to use both hands. I may want to use the conversion kit to LEDs as it seems like the bulbs burn out too often.