[xGS]

Halogen bulbs illuminate the road much better than LEDs can.

How so?
The "bulb" is just the light source.
The overall function of the lamp is also dependent upon the design of the lens and reflector.

 

[xGS]

Yellow light has much less reflection in fog or snow.

Not necessarily: Daniel Stern Lighting Consultancy and Supply

I changed my low beam to aftermarket HID and it's brightness helped a lot in the night driving. However, I am so happy that I left the fog light with stock halogen. It snowed here few days back. The HID's pure white light generated crazy reflection and I almost unable to drive. Then I turned on the fog lights and I can see the road in front of me immediately with the warm tone light beam.

Could be due to the difference in beam patterns more so than the color (temperature) of the light: Daniel Stern Lighting Consultancy and Supply