Technically, brightness = sqrt( .241 R2 + .691 G2 + .068 B2 ).
As you can see from the formula, Green:Blue perception ratio is quite clearly in favor of green, so the 1W green will be more visible to the human eye than the 7W blue.
This does not change if we consider special weather conditions (like fog, smoke); green will still be the most visible at least at the same ratio as in the formula.
@George Try China-town-like Shops/Malls (i.e. RedDragon). You will find at least up to 1W blues there.