There are few clear "answers" for color. "International Orange" aka Hi-Viz orange aka dayglo orange is used commercially, legally, for high visibility safety wear. So if chartreuse, aka "Lime" green or yellow, depending on who is naming it. (Since the human eye can't see yellow and it is up to the individual brain to decode it, there's objective reason why "yellow" and "green" may be subjective calls.)
In boating safety, the color of life jackets is debated for the same good reason. The hoods and visors of foul weather gear are often chartreuse, because it is never confused with natural colors on the water. You'd find that red, orange, and yellow all disappear against the colors of a low sun reflecting off whitecaps or the water. Green is less visible--but more unique.
But since the OP appears to be female...I'd suggest the extremely bright PINK SMDs that are out there. The color is very bright, nearly dayglo. Very distinctive. Unlikely to be missed or confused and very likely to draw attention.
Since I don't wear much pink, I put two big pieces of ScotchLite, the red reflective stuff, on the top of my SMD. *That* is much more visible than anything if there's light shining on it, day or night. Durable, inexpensive, comes in many colors.