HID......very good, very bright.
Also use a fair amount of power, and must be run through relays (if not integral)
Get hot.
You can retro-fit them into standard spotlamps for not an awful lot of money, but then, you're reliant on the quality of the original spots and their reflectors.....or you can buy HID spots, which are very expensive.
HIDs also take a few seconds to fire up to full brightness, so the 'normal' ones are not entirely suitable for use as a main beam unless you're prepared for that......there are fast igniting ones though, which apparently fire up to full brightness almost immediately.
HID units are significantly bigger and heavier than LED units
LED- Very good, just as bright
Use a tiny amount of power (sub 1 amp per lamp) so they do not need a relay wiring in.
Don't get anywhere as near as hot as HID's, nor is there any part of the circuit that's 20 thousand+ volts
A fraction of the price of the HID option.
LEDs also have a 'glittering' type effect, due to the modern pulse width modulation that they use...in effect, they are flashing on an off (Or bright to dim) faster than they eye can pick up, (which means they are legal) but the brain does pick up the twinkling effect, if only subconsciously.
There's no reason why you have to have either/or by the way- an HID conversion in the main and dip beam makes an immense difference (just make sure that the main at least is a fast ignitor type) then you can run LED spots/fogs as well.
For ease of use, compact size and tiny power consumption, I'd definitely go for LED spots/fogs, with HID dip beam (that's what I run on my own bikes)
Then again, I sell them, so I do have to admit to a degree of bias
Some examples:
£85 a pair
£100 a pair
(pinched from TunnerUk's thread, sorry Chris)
£130 a pair
My thread on the LED's I do is
HERE
