Orange digitata is probably your best bet. The ones I've had are very bright orange. If you're looking for contrasting colors then a Forest Fire digi may be good for you too.
+1 to the forest fire digi!
I have one, and it is very bright. To even add to its brightness, I placed it next to a Screaming Green Birdsnest to contrast the colors. Now, both of them really stick out, even though they are only about an 1" in size each.



