Osram Night Breaker H4 or Philips Xtreme Vision H4
I've used both of these over the years, and they're pretty much the same thing, but on the Boxeye the reflectors are still so poor that although they look bright for other road users they don't really project any decent light onto the road, which is why i added the spotlights as well which do a far better job all round.
I'm guessing there has to be some improvement on the Foxeye bikes, it couldn't get any worse! But having 2 x H4 bulbs will improve things straight away i presume.