The first Primark in Brussels opened a month ago and there is still a 50 meters queue to get in..
The biggest hit now is the new Primark store that opened a month ago. There is always a long queu to get in, they are counting people at the entrance and only let you in if enough people comes out. First I thought is was all for show, but when you get in it's so crowded that you thank god that they don't let more people in.
You can also find New Look (they have student discount), Pull and bear, Bershka, H&M, Zara, Pimkie, Women's secret, Calzedonia, Mango, Springfield and many more! There used to be a Forever 21 but it burned down and that's where now Primark is.
I personally like two brands that are less known: Sacha and Jennyfer. Jennyfer is fairly popular in Western Europe but no one knows it in Hungary. it is similar to New yorker if you know that brand. It is usually cheap and has some cool stuff.
Sacha is a shoe shop that sells the most fashionable high quality shoes. They even have Jeffrey Campbell and they sell nice accessories and awesome bags too.