Best malls for shopping in Hong Kong are the following:

Harbour City - on Canton Road in Tsim Sha Tsui. THE shopping mall in HK... with surrounding malls like Silvercord, The Sun Arcade, China Hong Kong City and 1881 Heritage you could find anything from outlets to budget to mid range to really high-end shopping there. Extremely busy everyday with shoppers you'll think that they hand out merchandise for free. There, one could find the 2nd largest Louis Vuitton in the world, the regional flagship store of Dior & Tiffany & Co are across the road from the regional flagship store of H&M, Another (a local trendy fashion brand with a bit of an avant garde touch) and a large enough Uniqlo (an economical Japanese brand)

Apple Mall - If you want the designer wear but don't want to torture your wallet with thousands of dollar, you walk into the inconspicious shops in this little hidden mall not far away from Times Square in Causewaybay. They sell the high-end fashion you find in the luxury department stores for a fraction of the original price due to close links to the manufacturers in China. But be prepared for cut off labels due to license restrictions. Address: 15-31 Hysan Ave, Causeway Bay

Pacific Place - Located in Central/Mid-levels. A 3 floor mall which includes mostly high-end stores. This mall is popular among travellers, though it's not very comprehensive for fashion shopping. It has an AMC cinema and a variety of restaurants, and you can try different Chinese and south-east Asian cuisines there. Has various stores for all ages. Great way to spend a day! The MTR (local subway train) runs through it for an easy access.

Sogo Department Store - Located in Causeway Bay on one of the busiest streets. It is a 15-floor mall which consists of both high-end and low-end stores (as in shop in a hole). Each floor is designated for a category. The ground floor mosty handbags/cosmetics (from stores like coach, estee lauder, nine west, max factor, prada, burberry, etc). The 2nd, 3rd and 4th are designated to women, men and children (stores including Tommy, Calvin Klein, Armani, Levi's, Disney and some Japanese and local brands). The 5th floor is for crystal and houseware. The 6th floor is a display of current events going on in Hong Kong. 7th and 8th is designated for bedding and furniture. The 9th floor changes approx. every 2 weeks depending on a fair or current occasion (e.g. it will have strictly coat/jackets during winter or swimwear during summer). and lastly the 10th floor holds electronical devices. The 12th floor is usually open for warehouse clearance. The MTR (local subway train) runs through it for an easy access.There is also a smallish branch at the Sheraton Hotel in TST

Times Square - Located in Causeway Bay. Another one of the most visited malls. It consists of 9 floors filled with mid-range stores like bebe, Marks & Spencer, Nike and many more. The MTR (local subway train) runs through it for an easy access.

Hysan Place - Located in Causeway Bay is the latest vertical shopping mall to hit Hong Kong just opening in August 2012.  This mall features mostly mid to high range fashion and life-style shops as well as Hong Kong's first 24 hour bookshop called Eslite. 

Windsor House - Located in Causeway Bay across from Victoria Park. Has a cinema within it, and has a Toys'r'u s store and an IT (a Hong Kong fashion conglomerate representing some European high end trendy brand) outlet. The mall also includes a number of stores selling children's clothing.

The Landmark - together with Alexander House and the Prince Building houses all the boutiques of Designer labels you may or may not name. It's where you will find the 2nd (as of its opening) overseas Harvey Nichols, the 4th Dunhill Homes, the 1st Asian Cartier store... etc 

New Town Plaza - Located in Shatin in the New Territories. now has low-end, mid-range and high-end stores. Very good for shopping, and the different phases of the mall means there's always more to explore. Two big Japanese supermarkets can be found here: Citysuper and Yata. Houses a UA cinema. New Town Plaza is connected to the MTR Shatin station.The regional IKEA flagship store is in the shopping mall Home Square not very far away

Langham Place - Located in Mongkok Langham Place shopping mall is a great indoor shopping location next to the Langham Place hotel. There are 12 or 13 levels of shops, mostly mid-range and speciality shops. On the forth floor is a nice food court (MOS Burger, Starbucks) area and to the entrance to the MTR station there is a group of bakers selling specialty cakes and nice treats. This mall is a nice compliment to the street side markets that make Mongkok a famous area for shopping in Hong Kong. When it becomes too hot or rainy outside, going inside Langham Place can be a great option when in Mongkok.

Festival Walk - Located in Kowloon Tong Directly accessible from the Kowloon Tong MTR station, this fine and attractive mall offers medium range (some higher end) shopping, good dining options, a great English bookshop (Page One), an Ice-rink, nice cinema and lots of good mall walking. Compared to many other malls in Hong Kong,Festival Walk never seems to bring the massive crowds, other than the holidays. Thus, you can come here for some peaceful, indoor mall walks where you can have a conversation with someone using normal voice and tone, not always an option in this noisy city.

City Gate - in Tung Chung (Close to the Airport). An outlet mall. also next to the cable car station taking you to the Big Buddha for a spiritual retreat after serious spending

Hong Kong is an excellent place to buy made-to-measure clothing. One of the legacies of the British system is a legion of skilled tailors, and inexpensive labour across the border in Shenzhen means you can get London-quality suits at Chinese prices. Still, you need a recommendation of a good tailor, as there are some fly-by-night outfits. Ask your hotel concierge or a local businessperson. Prices are on average about HK$280 for a cotton dress shirt and HK$2000-4000 for a fine wool suit depending on the quality of the fabric.

What to Buy

Eletronics, mobile phones and IT related things are not necessary a lot cheaper than in Europe or America... but they are all duty free and models are more advance. Try to stick to big chain stores like Boardway or Fortress and alike. They might not be the cheapest but then they will throw in a lot of free gadgets make you happy. NEVER EVER BUY FROM THOSE SHOPS ON NATHAN ROAD WITH BRIGHTLY LED LIT SAYS 'DUTY FREE'... They are most certainly a tourist trap

Street markets are mainly for souvenirs... there's Stanley Market, Ladies Market and Temple Street Market.