White or red probably doesn't make a big difference. It would be nice to have all the lights the same, so a spare could work in the front or back.

However, I don't see any reason to change red from the "standard". And flashing red seems distinctive enough. Certainly one doesn't want to annoy drivers, or blind drivers (no using my headlight in flash mode on the rear).

I think I saw elsewhere where it was suggested to use a completely different color such as flashing blue or green. But, of course, the police already use blue.