You mean your familiar paths... some of us have commutes that mix city, park, and unlit unpainted creekside trails (Stevens Creek trail, along the approach to the airstrip at Moffett Field, is intentionally darkened, twisty, tree-covered, and poorly marked -- did I mention the clusters of ninja pedestrians filling both sides of the path? -- and it lets out on either end to brightly-lit multi-lane expressways with bike paths).

If there was one good answer, there'd only be one kind of bike light.

(fwiw I'm pretty happy with 300w niterider helmet light and a cygolight "2w" hotshot taillight along with some random little blinkie accent lights on the frame that I think I really use just because they're lying around -- unified usb charging for all lamps is a big plus too btw)