I would like a light that's like an auto headlight - a low beam with a cutoff so as not to blind oncoming traffic, and a high beam that lights everything. Both need to be good enough so I can easily avoid road hazards and see large objects far enough away to react appropriately. Want a minimum 4-hr battery. Nice if it could be removed quickly & packed away to avoid theft.
I am still considering the German light units for the well-engineered beam pattern, even though the expense is high & total light output is relatively poor. May go with an LED anyway and deal with it somehow -- maybe by frequently riding in low intensity mode. May even still go with a homebrew halogen -- not sure how to get a cutoff design there though -- thinking low watt narrow flood 'low beam' & higher watt spot 'high beam'.
Got back into cycling a couple years ago & doing it seriously now - bought a Cateye EL-300 five LED light - brightness is OK given that it's a 4-AA light - however very disappointed at the narrow, narrow beam.
My riding is done in city & suburban areas - some lit roads, some unlit. Gently rolling terrain, mostly straight roads. Considering doing more mid-distance night riding but I believe the lights I have (EL-300 & smaller) are not good enough.