Well it depends on what you want a light for.
Headlights have different purposes.
The 2 purposes I think of are "visibility" or can the dern motorists see me?
And the other is illumination. That is can I see a pothole or a possum in the dark with this headlight?
I think an LED is a minimal way to go for some visibility. But a 3 or 5 watt halogen bulb is much better and will give a little illumination also.
Oddly enough, on really dark roads, you don't need much light for motorists to see you. Now if you were riding say on the strip in Las Vegas well you would get lost in the dazzle unless you were shooting off flares and fireworks.
I have found that most lights now seem to have overly wide dispersions so even a 10 watt or 15 watt has a wide angle beam that does not illuminate the road for much distance. That means that I can "outrun" the head light on a really dark road at about 17 mph.