Shopping in Bangkok is really enjoyable, with heavy discount & on top of that can also claim VAT at the airport.
Shopping in major departmental stores in Japan is also very enjoyable... with good discount and wide varieties of brand. There is no need to claim VAT at the airport because there are special counters at the departmental store to exclude VAT for tourists. So, get rid of the unnecessary hassle to pay first and then reclaim at airport..
More importantly, the staff are very professional, no hard-selling and guarantee no fake or cheat.