Depends on what you want the "fog lights" for.
Do you want to actually be able to use them for better visibility in fog and inclement weather, or do you just want them as cosmetic accents or for extra light output when the headlights aren't enough but you can't use the light bar?
There are pre-made plastic inserts you can use to add round projector fog lamps:
http://ecx.images-amazon.com/images/I/41NKN5KsL3L._SY355_.jpg
I'd say a set of those with brand name fog lamps and 55W halogen bulbs would be the way to go for use in actual fog or rain/snow.
If you just want accent lights, LED is probably the way to go, unless you have HID headlights, then HID fogs to match might be an option.