In front I used a Light & Motion Urban 900 3-4 nights a week all spring and summer until its mount broke irreparably right at the base of the light's body. The LBS was good enough to accept the return, and I replaced it with a Light & Motion Taz 1200. Its design seems sturdier, and I like its beam pattern even better. I would recommend it.

In back I have a CygloLite Hotshot Pro 150, and a 100 (150 on seatpost, 100 on rack). For many rides I don't bother with the 100, but like having it as a backup, or for if I start getting that paranoid feeling.

I've had complements from motorists on my lights. I was once even approached by a cop who wanted to know the brand and models so he could start recommending them in safety classes.