If you really want lights that help you see in dense fog, then it's best to get high power driving or fog lights, and mount them as close to the road as possible.
I know the beam patterns for fogs are different than driving lights, but the main difference is that fogs are supposed to be mounted closer to the road than driving lights soas not to have the light reflected back into the driver's line of sight in intense fog conditions. That being said, the stock setup of having the weak fog lights being able to illuminate ONLY WHEN the driving lights are illuminated is totally worthless and defeats the whole purpose of fog lights: which is to be able to see better in fog, not see the area 0-5' in front of you car.
Car manufacturers need to rename the stock fog lights.
Call them accessory lights, or "A $200 option for cool looking lights"
Ideally, high wattage (penetrating) 80w+ driving lights (white or yellow doesn't matter, that has been proven), mounted on or under your bumper, on a totally independant switch so you can turn your headlights off, would be perfect lights for driving in fog. I had a set of 110w driving lights, on a switch independant of the stock lighting, mounted on the bumper of my jeep, aimed downward, not up, used only in fog and heavy snowfall. They never blinded oncoming drivers and worked fantastic.