I hate flashing bright harsh LED lights at night, from the one time I encountered a bicyclist with one while I was driving in the opposite direction. They're enough to trigger an epileptic seizure in the wrong people. I firmly believe that lights that light your way, and lights that warn others of your presence, should be separate lights.

I also hate all LED car headlights. There is something in the quality of that bluish-white light that harshes out my eyeballs far more than the incandescent headllights they replaced.