I have three bikes in the garage right now... mine, and two friends bikes (I am working on rejetting them). One is bone stock (factor headlight, looks new). One has the aftermarket alien looking dual headlight setup. Mine has the number plate.
Bias aside, I like the look of mine the best, just a simple number plate. I also rigged a tool bag that is roughly the same size as the number plate, that I can strap on there with big velcro straps if I am ever going to be riding far away from "the tool truck". It seems to be a perfect mounting place, no handling problems, and it puts a little extra weight low and up front to hold the front down during hill climbs.