Triangle of light>Hi-Viz>Light Colors>Dark Colors
Of course there is always more too it than that, but that is my opinion simply put.
The ultimate answer is that there is no perfect solution. If people can't see (or don't care about) huge freight trains that have a very bright triangle of light, are painted orange, have LOUD horns, and cross at only mark crossings, there is less hope for motorcyclists.
'09 GSF1250SA Bandit