When given the choice between natural versus man-made, I’ve always tended to get the natural stones. It’s always just been a personal preference of mine.
But I agree that the same elements go into both types- and in most cases, I would never be able to tell the difference! 
The most important thing is connecting with the stone. And trying to avoid stones that were collected in unethical ways, like Franscisco mentioned. Or stones that are mislabeled and sold as something they aren’t- like @MeganB mentioned here, or in the dicusccion Is Selenite Really Selenite?
A very interesting topic- thanks for brining it up, @Missa! 