I bought the pink at the local OSH -- it's bright and can be seen from quite a distance. The greens blend more with the environment, but sure wouldn't be seen or noticed as much. I had to order them on-line, since they aren't as visible, so not in much demand.
So I guess it is up to you which color or colors you choose. I'd say choose a color depending on your mood for the day.
I put them on my hiking poles since they are visible both from the front and the back. I'd personally use a pink and a green -- but I'm not sure why.
