I used red/orange till I realized I hated it. While I remembered to look at the front sight again, I took too much time looking at the front sight. While my times were a bit slower, my hits were a bit better.
At the 99 nationals I spoke with Todd Jarrett at length about them. Then Robbie chimed in also. Their dislike for them was different than mine. Not many of the top dogs use them.
If you have older eyes though, go with red. Especially if you also shoot open.
I prefer green. My eyes seem to aquire the green sight faster than the red. I'd also suggest going with a .090" blade from Dawson. The small fiber optic is contained in what's essentially a target blade. This gives better precision on longer shots than the sights with an oversized rod that disrupts the outline of the sight. If the rod breaks on a Dawson you still have a good useable target sight. Just my .02.
Each person's eyes are a little different. Some people see the red better some the green. I sell mostly red or green and some yellow. The people that buy red swear it is brighter the people that sell green swear it is brighter. You will also find the top shooters either recommending against fiber optics or recommending fiber optic sights that are thin. These shooters have excellent near sight and can focus on the front sight with clarity. I sell most of my sights to shooters over 40 years old whose eyes have started to loose their ability to focus on things that are close. You don't need a thin front sight if you can't see the front sight. When you are shooting a fiber optic and you can't focus on the front sight all you see is a dot. The diameter of the dot is what is important not the width of the front sight because the dot is all you see. The fiber that I sell is 0.060 it holds up better and gathers more light, the width of the front sight is 0.125 because the blade is sturdier and holds up better. With the design of my sight you can mushroom out the diameter of the head of the rod anywhere from just barely over 0.060 up to the width of the sight. Bottom line on color is try both and see which you like the best (my sights ship with 3 inches of red, green, and yellow fiber.)