After 6 years of commuting, on and off-road, I think I have spent more money on lights than on cycling clothes and shoes. From cheap Chinese light-in-a-box helmet mounted ones that work very well to über-expensive CatEye external battery crap lights. The best compromise I found is an 80 euro USB rechargable, easy-detachable Trelock LS-950 with 6 levels of brightness and an lcd display to display its battery life.
This light comes with a fabric strap and a clip mechanism that pulls it to tension around the handlebars. Works great on round bars but not so well on my new monocoque aero bars on the Chiner.
The problem with the original band is that it’s a little too flexible allowing for the headlight to move up and down, touching the handlebars with the release button resulting in losing the light whilst riding. So we need a little more solid of an attachment. I had a great mount from a Sigma light (another rubbish external battery one) so I did some cutting, drilling and gluing. Badda bing badda bang: my rides are illuminated.