In Asia, I would say it's definitely Taiwan. Hong Kong used to be cheaper but not anymore. Plus, you get another 5% VAT refund in Taiwan. Friends from Taiwan used to fly to HK to buy jewelry, cosmetics, fashion brands but now they don't bother coming out here anymore.
Your input, ladies is great! I enjoyed reading the answers! Thank you! But what I meant by my question was a "global answer"...what do you think which country in the world is the cheapest for Hermes and other luxury brands?