Several years ago I was a couple blocks behind the brightest rear light I had ever seen. I chased the guy down (<pant> <pant>) and asked him the brand. It was a Dinotte 300R. I persuaded my wife to get me one for christmas. It is amazingly bright. I can see it reflected in signs several blocks behind me; I keep it aimed slightly downward so as not to blind drivers.
It's a bit heavy compared to other lights because its body is solid aluminum, but it is a solid piece.
I see it has been replaced by THIS model, which I have not seen... but I don't doubt that it is bright.
Now, for full disclosure, I no longer use the Dinotte as much for commuting because I use it on my road bike. I use a Vizy light on my folder. It's not as bright, but it's more than adequate. It's lighter and requires less frequent charging.


The Dinotte 300R



The Vizy



The Vizy projects light on the pavement. This is washed out during the day, but seems like a good idea at night. The rear-facing light is visible during the day.