Ho Chi Minh City or Bangkok?

Bangkok, by far. You'll find much better variety and at least 1000 times more than you will in HCMC. The quality can range from poor to very good in either city. You don't see nearly as many people selling knock-offs in HCMC, the Ben Thanh Market is the best place, otherwise you'll find some at stores around District 1, but not even close to what you'll find in Bangkok. In Bangkok, you can find counterfeit clothing, watches, dvds, sungles etc. at places like the Patpong Night Market (huge), the street stalls in the Pratunam area (along Ratchaprarop and Petchburi Rds.), along lower Sukhumvit, the MBK Mall (5th fl. is the best place to look), and many of the open markets all over the city. Pantip Plaza and the IT Mall are good for pirated software and dvds, although I'd avoid buying dvd's as the quality can be very poor although some are fine. Most shoes aren't very good either. Bargain hard.