Clearly red is the winner.
Actually... it's the location. The hummingbirds prefer the one nearest the corner of the house regardless of color, even though they are only three feet apart. When the awnings are extended, even that little bit of separation makes the inner one seem to them more confined and less easy to escape from.
They are very shy and cautious. Just walking by inside the house (the wall is glass 8.5 feet tall) even though I am ten feet away they all scatter and fly away, only to regroup within seconds.
If I allow the feeders to go dry (I'm going through a gallon and a quarter of nectar per day now) they abandon the feeders except for the occasional scout. When I refill them, in less than a minute there will be a dozen (or more!) birds back feeding. Pretty cheap entertainment.
tanstaafl.