I like the build quality of the Hella 4000, which I use with the Euro beam, but I prefer the light output of the 8" KC Hilites with the driving beam. The beam patterns are quite similar. Both have lamps in the 130W range, both are about the same size lens, both are round which tends to maximize light output. Both are under $300 a pair. As I recall, the Hella did not come with a wire loom for installation, but the KC's did, so by the time you add the wiring accessories to the Hella price per pair, it works out about the same either way.
If you are considering upgrading a light like this to HID, the Hella is a better candidate due to housing construction and depth. The KC unit can be purchased in HID, but the HID version adds a body ring to the housing to make it deep enough to take the HID bulb. Without the ring, the standard halogen housing would be too shallow for the HID installation. The Hella is already deep enough. I see no real differences otherwise between the HID and halogen lens and reflector assembly in the 8" KC units.
I don't use fog lamps, so someone else will have to give their opinion on those.