some guidance as to your budget would be useful.
A very useful source of info on battery powered bike lights and torches is torchy the battery boy's website
http://www.torchythebatteryboy.com/
I bought a pair of Torchy brand Cree XM-L T6 jobbies off him from on
ebay where he is big_f_d_d complete with a uk charger that won't burn the house down while you sleep, and got a penny change from £50
delighted with them. they cope with a country lane dark/night time commute with ease and run for around 90 minures on full power, though the third level is ample for me.
EDIT I should add that after three weeks I swapped the supplied mounts, which do a very good job and would be perfectly fine in most drop bar situations, with ultrafire velcro ones simply because one of the supplied 'bolt clamp' mounts slightly fouled my cross top brake lever on my bullhorns in the ideal position.