I don't think HKG airport has the best price IMO. For Whiskey in general you get better price in TPE airport (or even down town with small tax, unlike 100% tax in HK)
I would recommend
1. Buy Whiskey in downtown TPE and check-through to YVR
2. Buy Whiskey in TPE airport, put in plastic sealed bag and transit in HK (You may have issue if flying CX 888 as it continues to JFK)
3. The last is to get it in HKG airport