I recommend H4 halogen 55/60 Watts in a good reflector like Hella, Bosch, Cibié or Maréchal. Best bulb by far is the Philips X-treme Vision Moto. If you're concerned about draw (I am not) you could choose the Philips Ecovision that performs better (and lives longer) than a standard 55/60 Watts halogen but draws 20% less. If you ride in daytime only, Led could be an alternative. For night riding I do not recommend Led, that is: not before I've seen test results that suggests they're better in every aspect. Brightness in itself means nothing.