Twin XML (LED) is this years forum favorite, single XML (cheapy chinese or the likes of gloworm x1) units are still available but I went for the twin, as they cost little more and are a lot better beam wise.
Gloworm look great but are £170
Gemini duo, similar system and again look great £170
Luminator is similar twin XML unit and only £123, a chinese import but checked and have great support from MTB Batteries (and no bad battery/charger rep).
Cheap and cheerful (or not) option:
Solarstorm X2 a twin XML unit (other types are available), ignore the stupid lumen figures, really the output will be similar to those listed above (the beam might not be as refined), costs aprox £25-35 off ebay. Batteries and chargers 'can be' suspect (I have to say that but have never personally seen or heard of anyone I know real issues but there are forum posts about it), potentially you can get replacement batteries/chargers for another £28 from ebay sellers like Big_f_d_d or for greater piece of mind.. MTB Batteries for £68. All of a sudden the bargain isn't such a bargain but that a 'worst' case senario... most ppl's work just fine. I would recommend choosing a UK based ebayer, so if you do have issues, it can be resolved quickly.