I usually mix and match these 4 brands alot.

How I categorize these places in ym head:

Topman: Very High-street hipster stuff
Zara: Affordable runway substitutes
Uniqlo: Simple every occassion wear
H&M: Casual+High street designs

Zara and Topman are in the more expensive segment while Uniqlo and H&M are more affordable. The main difference is 'you get what you pay for' in terms of price vs quality.