Depends on the situation.
G kiting is pretty standard, and is best used when you are in a dangerous situation and speed is completely necessary. Works best because while lag does affect the timing, it doesn't change how fast you run, as it does for the other kinds of kiting.
Then there is H kiting, backwards. The only reason to use this is in a situation when you are in little danger from the thing chasing you and would prefer to kill it if possible. Also, lag should be minimal. The reason to use this is in situations like say, you are at full health being chased by a single sword in a map like grass hills. You dont want to be hit, but it would also be preferable to kill the sword should it suddenly switch direction and attempt to escape. since you are using h, it is slightly easier to quickly change direction after you kite so that you maintain some proximity to him, and are able to finish him off. This is just based on my personal experience and preferences though...
For forward kiting, as DAZ said, right clicking both for the moving and attacking is preferable, since you are able to choose the target ie. a weakened sword vs a strong one or edge archers in a spear archer build. of course H or S kiting can also be used when it doesnt matter what you hit and may or may not be faster for you than clicking.