i've been very happy with my blaze2w, reliable, thrifty with a pair of AA, water resistant (not waterproof), and reasonably bright for around town. the downsides, you can start to outrun the light anything past 10kmph, the amount of light just isn't there.

also quite frustrated with the handlebar mount. the quick release cam latch disengages occasionally, and i have never been able to get the mount tight enough that the light won't keep slipping down. cam latchs are really convenient but this design just doesn't work.

i have to secure with rubber bands to keep the light from moving.