i think it would have to be starboard.
they cater for kids like no other company with a holistic approach. boards, sails, booms, masts etc.
plus they have the pro kids range for the more advanced.
also the loft sails and ezzy sails kids rigs are also excellent.
important thing is a rig from 3-1.5m which is soft. so undersized wave sails aren't really appropriate.
the windwanderers are using the starboard kids rig and i am very impressed with it.