I strongly recommend Mine's place. Though it is a shared room, it is very tranquille and your space is well respected. Mine was very kind to offer innumerable number of teas during my stay and also a meal when I arrived tired from my journey on the first day. As far as the location is concerned, it quite well connected with bus and trains and is peaceful and green. Brussels Central won't take you more than 30 mins if you schedule yourself well. I would strongly suggest you to stay at Mine's. She also has a private room.