I am not a big fan of the Safari and find the geometry kind of strange even for a bike designed for trekking bars.

Can't go wrong with the other two choices but I would recommend you consider a bike with a compact geometry for your son since he still is growing. If you fit him on a bike that has a horizontal TT like the LHT, he won't have much room to grow. You can usually go up a size on a bike with w/ a sloping TT since you still have stand over clearance and just go with a shorter/negative rise stem to start out with. As he grows, raise the saddle and change the stem.