Have been teaching my son aged 14 for the past year
and he is now making fairly rapid progress.

His current board is a Starboard Starsurfer 127L,
but he has been on my Fanatic Falcon 104 and using
sails from 4-6m coped very well with it.
He is comfortable in the harness but not yet in footstraps.

His weight is 52kg and 5'3''.

Am looking for suggestions from others who have taught
youngsters about which board to get next and which to avoid.

He is going to continue on the Starsurfer whilst he is sorting
out using footstraps (plenty of options on position).

Thanks for reading.

The Starsurfer is difficult to learn to plane on (it is heavier because it has a lot of features). I'd put him on a 90 litre freestyle board (but your Falcon should be OK too) just for a few goes till he gets planning in the footstraps. Then I think the ideal board for him would be a 70 litre Starboard S-type. There are not many good all round boards for his size as most of them are wave boards. The S-type has 3 and 4 strap options. This board is from around 2005 so shouldn't set you back too much if you find one.

Thanks for input, hadn't considered a Freestyle (probably
i am too old for it) board but certainly sounds a good option.