My 2012 Prius had projector halogens, and a cheap HID retrofit (H11) worked well. That said, it will be the last HID conversion I do because I measured my supposed 35W bulbs and found they draw closer to 55W, which is the same as a halogen bulb. I tried a cheap LED conversion for the H11 bulbs and the plastic tabs broke off even with extreme care in installation. My conclusion was that any bulb that is held on by twisting it into the housing cannot use plastic tabs, as they will break off. They need to be metal tabs. Also, the LED bulb light pattern was extremely poor in a projector housing.
That said, my motorcycle uses H7 bulbs in a reflector housing, and those are held on by a metal spring clip. Since it doesn't rely on twisting the bulb into the housing, there is no risk of breaking plastic tabs from cheap LED bulbs off. LEDs turned out to consume less than half (15 watts each) the wattage of halogen, and gave much more light output. The light pattern in the reflector housing was good.
Conclusion:
LED bulbs consume much less energy and work well in reflector housings, but not projector housings.
HID bulbs don't save any energy, and are more complex due to having to mount the ballasts, but work well in both projector and reflector housings. Probably not worth the effort though.
Here's the LED bulbs I bought for the motorcycle:
https://www.amazon.com/gp/product/B0...?ie=UTF8&psc=1
Finally, LEDs seem to only be sold with a color temperature of 6k, which is too blue for my taste. I'd prefer something more around 4k, but haven't found anything.