Actually, as an iPhone user, my favorite editing apps are AirBrush, VSCO, and Photo Relive. I use AirBrush for touching upon my features(you know that one perfect photo of you in which you have a horrible pimple? well, this is the solution). I like to use VSCO(which was made pretty famous by teenage girls back in the day) for adding filters and playing with the light, colors, saturation, grain, etc. Next comes
photorelive.com, which is the ideal app for bringing life to a picture. I like using it when I have a photo taken from afar, making it clearer.