I like "flashing" LED lights, because I think they catch drivers' eyes in the "urban clutter" of lights better than just a headlight. I have tried several, and have a bunch of the Planet Bike single LED lights on various bikes.
Yesterday, I bought a SIGMA Sport TRILED flashing light. Three LED's and a focusing lens behind them. It uses three AA batteries and is rated for 120 hours. (Such ratings are based on something like "how many hours until the light is 50% as bright as with new batteries). It is designed to simply "clip" to the front bar with its own oval clip - no tools are needed to put it on and no tools are needed to change the batteries. List is about $20.
I tried it out at noon, and it was too bright to look directly into the focusing lens. Then, I was riding at about nine p.m. A guy walking on the sidewalk headed for the curb, about to "jaywalk" across the street in the middle of the block. As he glanced to his left, he came to an abrupt halt, and said "Whoa, THAT is a quite a light you got there".
The Sigma lens is designed to be seen from the sides as well as the front. It is a bit distracting for the rider as well. I will probably put some black electric tape over the top of the lens to reduce the distraction factor. All in all, this is the best "blinking" LED light I have seen in its $20 price range.