I agree with the previous posts so far, the true "Genre-defining" Classic SF's are;
6P - where it all began, this is the Macintosh 128k of lights, it started a revolution in high-performance, pocketable lighting technology
A2 Aviator; first regulated incan, succesful integration of LED and incan, soft-start bulb tech, wide flood and throw in the same light, with no need to refocus
the Executive series; extreme modularity and customizability in an even smaller, more pocket-freindly size
M6 series; spotlight power in a small package