Yupp, here I am:
Five teenagers: three boys (13, 15, 18), two girls (14, 17) and a young woman (20).
I am quite happy: just now (that is for the past 3 - 4 months) they have been very comfy companions.
However, the time before that ... that did give us a run for the money.
I agree, that parenting is not for the faint of heart, OTOH, there are very few activities that are so rewarding. I think sometimes that the kids teach us more than we teach the kids. But that is the nature of youth: repeat most of the mistakes of the parents and then add a few of your own.
I agree that the younger ones are more easy. That may be the result of experience with the older ones.
I am also very proud of all the kids. They do well in matters moral; they know right from wrong, include ethical thinking and they more often think before they act than before.
One is on her way to become a police officer (which is a university education in Sweden), one is already planning a career in science, two are very talented musicians (who earn some money using their talent), one is just great in design. Only the youngest is more of a child - which is as it should be.
I would not call myself old. The kids keep me young and flexible in my mind. And that I am grateful for.