HID is still better thus far. LEDs have alittle more to go as far as evolving before they can even the playing field.
I will say that LED projectors are now available but they aren't the same as an HID projector. hID projectors use a bowl to reflect light, the bowl full surrounds the HID arc. LED projectors like found on the new Toyota Corolla, and ACuras use a half moon style projector, a single high powered chip sits on a giant heat sink and all the light is thrown upward 180* and the light is reflected in the top half of a bowl and then forward through a lense. LEDs aren't as bright as HIDs yet and that's why multiple LED projectors are used to compensate like in the ACURA jewel headlights. The corollas use a single LED and are very bright but don't quite equal an HIDs.
For those of you that think LEDs create less heat you are correct but only on small scale really. The power required to creat the lumens necessary to be a headlight creates ALOT of heat. This is why the LEDs are mounted to very large heat sinks. For whatever it's worth HIDs don't create that much heat where they would require a heat sink, LEDs do otherwise there efficiency/brightness would go down the drain.
The way it has to be is... LEDs require LED specific optics, HIDs use there own specific optics but can also work decent in halogen projector based optics as the HID arc will usually be in the same position/placement as the halogen filament. So in short, halogen reflector housing u should only run a halogen bulb, halogen projector u can use halogen or HID but HID will perform better in a HID projector, HID projector use a HID bulb. Leave the LED drop in bulbs for fog lights and other non essential lighting as they haven't earned there place to be used in headlights due to the optics. If you want to use LEDs in the headlights then figure it a way to retrofit LED projector optics. But given the current headlight designs it's not really feasible.
