Generally, you will find PPL training in Belgium less expensive than in the Netherlands. Particularly so that in Belgium most fields have a club where you can join as a member. Whether that is worth the longer travel is up to yourself. I would recommend you to visit a couple of fields and judge for yourself what you like and what not.
Do not be confused about Sabena Aero Club, they are really a club, not an academy. At one time there was some kind of tie with the Sabena Airline but it is not clear to me if any of this was passed on to the present Brussels Airlines. Their planes still proudly carry Sabena's S-tail logo!
One real academy in Belgium is BAFA at Antwerp Airport EBAW.