I wanted a light for commuting, that did not necessarily throw a searchlight beam, but was good for twilight times. It had to make ME visible, rather than enable me to see. I watched other very visible commuters, and decided that the light needed to be white, very bright, and flash. Ideally, I also wanted a rechargeable model. My current light was the antithesis of all this, and only seemed to last for about 2 hours on a new set of batteries.
Enter the Planet Bike Blaze 1-watt. Very white light, very bright, has 1/2-watt, 1-watt and flash mode. The flash mode is also a pulse flash, making this light even more obvious to night-blind motorists. I aim it about 5-6 yards ahead of me, and it lights up road-signs half a mile ahead. It has a good lateral dispersion, too. Not rechargeable, but I am now using rechargeable batteries. Has already gone over 2 housr with no sign of failing.
I tried this against all the bike lights at LBS, and it was the brightest. Not sure how it will work in full dark, but looks good so far. Excellent for rain, twilight, fog and various low-light conditions. For full dark, maybe combined with a high-intensity spot?
Ironically, the really bad light I am swapping out... was also a Planet Bike.