Due to the way my itinerary is set up, I went with PCCW all in one sim card for 198 hkd. It's also available in the 98 hkd version.
My itinerary is as such: 3 days HK, 7 days in Malaysia and Thailand, 3 days Macau, 3 days back in HK.
There are a variety of data plans for this sim. Since I had a late arrival, I had to get the sim in the morning (went to Tsim Tsa Tsui location).
I got the 1 day data pass (18 HKD/600 MB) for two days. When I get back I will probably get 3 day pass and roam in Macau (haven't made up mind if I want to get ANOTHER sim there). Data passes include unlimited pccw wifi as well. Pay as you go is 3 hkd/MB.
Very good reception, the 3g is supposedly faster than other networks (up to 42 Mbps). I get my H+ symbol, I'm happy.
Currently posting from my Malaysian sim. I'll be picking up another when I get to Thailand.
For reference, I have the Samsung Galaxy S4 from Verizon. It's already sim unlocked, you just have to put in the apn yourself. I suggest writing or printing out possible telco apns you will use to make sure your data works before you leave the counter (for example, Celcom in Malaysia put in the completely wrong apn for me).