It really depends on what you want the lights to do - some people just like how it looks.
First lets' discuss beam patterns - there are (or used to be) essentially three types of beam pattern - fog, driving & spot.
Looking from above fog lights have a wide angle beam and will illuminate both sides of the road, looking from the side, the beam has a sharp horizontal cutoff and goes downwards onto the road directly infront of the vehicle - the idea here is that the light is aimed downwards on to the road without limited reflection off of the fog and back into the driver's eyes - because of the beam pattern, fog lights have a limited range and are normally mounted low down, at or below bumper level.
Spot lights perform a different function they have a very narrow beam (viewed from either above or the side) and are intended to provide visibility at a distance.
Driving lights fall somewere between the two, a wider angle than a spot and greater range than fogs - and there are also different types of driving beams.
You can get all of the above patterns in halogen or HID lamps, and you should be able to get driving & spot in LED, along with another beam pattern known as flood - which as it suggests - floods the area with light.
You can use halogen lamps however, they have higher amperage draws than either HIDs or LEDs - if you go overboard on your lights, you'll definitely need an alternator with more output - it becomes a trade off though - you either pay more for the lights, or you pay more for the alternator.
One thing I will suggest - whatever you purchase, pay more for quality - the cheap stuff is exactly that, cheap stuff. Personally I use the Hella Comet 500, when a company can have a product on the market for over 25 years, you know it's a quality product.
