Which dinghy for sailing with a child?

I've had some incredibly memorable sails in my life.  Last race of the 12' Skiff Nationals, and winning the event.  Winning a monster windy pursuit race in my Fireball.  First flight in a Moth.  Top 10 windward mark rounding in the 18 at the Mark Foy trophy in amongst the pros.  Going blasting at Weston (as per my avatar) when racing had been called off due to the wind conditions.  And that's not even counting the big boat stuff.  But I have to say just reaching backwards and forwards with my lad in a cheap old Ent made out of dead trees. and seeing his face and excitement, with him asking to stay out for longer, and telling me how much he loves the boat and when are we going sailing next, tops the lot.