I divide bicycle lights into two classifications: Seeing Lights and Be-Seen Lights. A seeing light is a light you use to see where you are going. A be-seen light is one whose purpose is to increase the odds of someone seeing you.
For seeing on my urban commute I'm pretty happy with my Wildken Smart Headlight. It has a great beam pattern and the amount of light it puts out is based on how much ambient light there is. It auto-dims when there is an oncoming light, and auto brightens when I ride through dim underpasses.
On kind of dank, rainy days, however, the Wildken needs help. The "smart" light rightly figures that I have plenty of light to see by, but I want to help the drivers behind rain-smeared windows see me. For that I use a couple of Ascher USB rechargeable lights. I got these little guys as an impulse purchase, something I added to another order to reach a free-shipping threshold.
I've been pleasantly surprised by them. They cast a broad, diffuse, bright light. Lousy in terms of helping me see the road ahead, but perfect for drawing attention to my bike. They are not blinding to oncoming traffic and they last a good while on a charge. And while they are inexpensive, they don't feel or seem "cheap". They come in a nice little box with extra rubber mounting straps and so far they've held up fine to a damp Oregon winter.