A lot depends on what you want the lamps for.
Fog Lamps - Fog lamps should be mounted as low as possible to prevent the light bouncing back and allow you to see "under" the fog. They are designed specifically for inclement weather conditions, and are of little use for regular highway driving in normal conditions. However, when mounted high on a vehicle, they can make a good off road light source, as they illuminate the area close to the vehicle very well, which is useful when moving slow.
Driving Lamps - Driving lamps make a good all round lamp for both on road and off road use. They illuminate reasonably well into the distance and also provide a good spread. If only one set of lamps will be installed, and fog lamps are not required in your area, then driving lamps are the obvious choice.
Spot/Pencil Lamps - Spot lamps are ideal for highway driving as they move your focus far ahead of the vehicle. They can be useful on the trail when looking far ahead, especially when moving fast, but their primary use is for freeway driving.
PIAA make great lamps, but for you pay for them. The new ProComp lamps are not bad, Delta make some good value lamps also.