The best powerful torches are umbilicals, where only the bulb unit is carried by hand, while the battery unit is tucked away somewhere discreet. The best way to mount an umbilical torch is on a Goodman handle type system, that puts the bulb on the back of your hand and therefore leaves your hand free for other things.
HID lights are recent additions to the market: These are wonderful things that put out brighter and whiter light than a standard bulb, using only a third to a fifth the power (depends who you ask). Combined with the new NiMH rechargeable batteries that have also started being used, very small, very powerful dive lights are available. Sadly though, they are very expensive.
Not much to choose from between small torches, though the UK SL4 and Halcyon Scout are very popular.
I use: DIY umbilical torch, 20w halogen bulb; two Pelican SuperSabre backup lights.