Short answer

• For most Australians the best overall online fashion store is THE ICONIC — biggest local selection, fast local fulfilment, free/cheap metro delivery and easy returns. (en.wikipedia.org)

Who is best for what (quick guide)

• Best all-round / fastest local service: THE ICONIC — large range of Australian and international brands, strong fulfilment network and customer-focused delivery options. Good if you want one place for everyday brands, sportswear and designer diffusion lines. (en.wikipedia.org)
• Best for international fast-fashion and trend-led items: ASOS — huge trend selection and a local Australia site/fulfilment options, though reviews on service/returns are mixed so watch delivery/return rules. (ASOS.com)
• Best department-store experience / premium Australian labels: David Jones and Myer — better for higher-end Australian designers, department-store ranges and omnichannel (in-store + online) services. David Jones has been investing in its app/online experience. (theaustralian.com.au)
• Best budget / basics / fast-turnover: Cotton On and similar Aussie chains — wide availability, low prices, frequent sales.
• Best for luxury / designer: Net‑A‑Porter, Matchesfashion, Farfetch — if you want global designer labels rather than everyday Australian brands.

How to pick the “best” for you

• If you want fast delivery and easy returns in Australia: prioritize THE ICONIC (local fulfilment). (en.wikipedia.org)
• If you care about price and trendy pieces: compare ASOS and local outlets during sales, but read the delivery/return T&Cs first. (ASOS.com)
• If you want premium Australian designers or omnichannel support: check David Jones/Myer product ranges and apps. (theaustralian.com.au)

If you want, I can:

• Compare 3–5 specific stores side-by-side (shipping cost, returns window, typical delivery times to your postcode), or
• Help find the best site for a specific brand or type (activewear, formal wear, luxe designers).