I really like using the Medela Pump-in-Style but it is quite pricey so it really depends on how you plan on using it. If you are returning to work and need heavy duty pumping, then this is the one. But if you are a stay-at-home and plan to only express once in a while, then I heard good things about the Aventi Isis, which is only about 1/4 of the price.
Also, you may want to consider buying the Medela online, if that's the one you go with, as it is a lot cheaper than buying it in the stores here. Medela came out with a new hands-free electric doublepump called the Medela Freestyle, which is supposed to be even better than the PIS but it's not sold in HK so you need to order online.
Btw, if you do go with a Medela pump, you will end up using the Medela bottles for collection. In which case you don't need to buy different bottles for feeding the baby, you just need to fit the Medela bottles with the Medela nipples (other nipples could work too but may leak). Personally, I made the mistake of buying a full set of Tommee Tippee closer to nature bottles before I gave birth but then, I got stuck with two sets of bottles, and am always transferring the milk between them (just to make some use out of the Tommee Tippee bottles.) Which is super silly as my baby doesn't seem too fussy about which bottles I'm using!)