I have some experiences with below shops and most of the people will keep tell me about those shops.

PRIMARK (Cheapest)

C&A

H&M

ZARA (Best in Jackets)

INNO GALLERIES

PULL&BEAR

ZEEMAN (Many Branches)

KRUIDVAT (Very few collection)

HEMA (KIDS, WOMEN and all type of Accessories)

JULES (BEST FOR MEN)

LEVIS

DECATHOLON (SPORTS WEAR)

CORA (ALL IN ALL CLOTHING,TOYS, GROCERIES, FURNITURE, STROLLER for kids)

https://www.bel-bo.be/

https://www.underarmour.eu/en-be/

BRABANT SHOPPING STREET (For large running clothing with measurements) Address:  Rue de Brabant 107, 1030 Schaerbeek.