For the two bikes that I'm most likely to be riding in the dark, I have a CatEye EL100 3-LED light. For the rest, I have a CatEye EL400. The 100 has better mounting hardware, reflector design, and side visibility. On the other hand, the EL400 uses a quick-attach strap that makes it easy to move around to different bikes without having to have a bracket on all of them.

Both are fine for straight-ahead be-seen use and in a pinch can provide some path illumination in the dark. I've used them on unlit MUPs and even in the forest.