Coming from a TKD background (and now training in MT) I've got to say that MT kicks are much stronger. I still love TKD though and I agree it is a good martial art to start at a young age, it helps immensely with flexibility and learning all the fancy spinning flying kicks is cool for demo shows! Unfortunately we weren't encouraged to punch/box properly, so hands down most of the time and since it has become an Olympic sport, we've had to put on loads of protective sparring gear and go on point system -- which you can't really apply to real life situations.
I didn't think I'd like MT, as I saw how hard the kicks were (they seem to be meant to break your/your opponent's bones) and I didn't really fancy not being able to walk after every training session! A year on and still struggling to learn how to block with shin (owie owie owie) I'm amazed I'm now encouraging my TKD friends to try it....the first video (tkd beating MT) the 'MT' guy just didn't look confident at all, proper MT would just go for the muscle side of the thigh or shin and that would be the end of it.