The only fully studied area of this topic is within shaving and depilatories. Studies show that these methods are the only hair removal methods that are guaranteed to not change the character or growth of your hair.
Which method lasts the longest?
Hair removal methods that pull the hair out at the root, such as plucking, waxing and threading, all tend to have a longer lasting effect. The unfortunate part of this is that these are all the more painful methods, and in some cases can be skin irritants. This can be difficult when it comes to removing hair in sensitive areas like the face.