Each platform has a genuinely different risk/effort/audience trade-off — there is no single “best” one:

Platform Best for Trade-off
WhatsApp/Instagram catalog Zero capital, local trust Manual, doesn’t scale past a certain order volume
Shopify / WooCommerce store Full control, your own brand You must drive your own traffic
Etsy Built-in buyer intent, handmade/niche goods Restricts pure generic dropshipping; favors print-on-demand/custom items
Amazon Massive built-in traffic Strict dropshipping policy — you must be the seller of record, not just relabeling AliExpress
TikTok Shop Viral/impulse-buy products, younger audience Trend-dependent, product lifecycle is short

A common, sound strategy: validate a product offline or via a free catalog first (Module 1–2), then commit capital to a proper store (Module 5) once you have real proof people will pay for it.