I just bought a B&M IXON IQ and it's superb.
4 x AA rechargeables.
Nor quite as bright as my dynamo-powered Cyo but almost.
I've had one of these for over a year and I agree they are superb.
Watch out which rechargeables you buy though. Some of them lose their charge in a couple of days, even with no use.
The Sanyo Eneloop or similar low self-discharge batteries will last a lot longer.
(In summer, I leave the light in my work bag in case I get stuck at work, but usually right home before dark. So it can be a few days between charges.)
I've got the light mounted on a Cat-Eye device which is a brake booster mounted on the canti pivots with the top horizontal and expanded to the same diameter as a handlebar. Looks inelegant, but puts the light where it belongs, just above the front wheel. These mounts seem to have disappeared from the Cat-Eye catalogue.
B&M do a mount for the Ixon which can be attached to the fork crown, but it won't work with cantilever brakes, and would be tricky with V-brakes (except where they are mounted behind the fork, of course.)