Cree T6 deal extreme import version: Could I suggest you buy a fresnel glass for it too to replace the plain one, it'll give you a better spread of light onto the road for your own benefit & won't dazzle the 2 ton of metal coming at you as much.
I use a cateye volt 300 as my to see by light in pitch dark country parkland on my Brompton, so fairly slow 10-12mph pace,
I like it a lot as it is very compact & easily pocketable, spare mounts are £3 a pop in
Evans for other bikes, it has a good battery, USB charge at work during the day if needs and for better lit bits, it has the dual steady/flash mode that works pretty well with the 300 lumen flash and lower power steady setting. Also the volt 50 rear battery is interchangeable so if you had the set and found yourself out of juice mid ride, you've got an instant replacement power pack (300 v 50 output so the rear lasts much longer on a charge) - just need to remember a spare back light in that eventuality
I see that they've brought a more powerful Volt 700 out. if the 300 is a benchmark, then the 700 will be a hugely bright light and well worth considering