Furniture is really personal, you gotta find something you woudn't mind using / facing every day, so its gotta be functional and pleasing to the eye and hopefully not break your bank account either.
Like almost everything else, HK offers a variety of choice for everyone (someone's gotta be buying that tacky stuff):
Queen's Rd E is actually WanChai, and Lockhart Rd is more for hardware supplied and some furniture shops mixed in. I'm not sure you'd want to buy a mattress in MongKok when you can get a good simmons/sealy, etc where you know what's inside. WingOn is a dept store that used to have a furniture section upstairs (Day One?) but its since closed, and the furniture stores in Times Squre have also moved out, its all hi-fi and electronics in the upper floors now.
Other than high-end european imports or chinese antique replica's, there always Ikea of course.