Without knowing your specific needs, it's hard to say exactly, but it sounds to me that you're not getting an incredibly high number of miles per year so expiration before you're able to redeem for anything meaningful could be a real problem for you.

If that's the case then you should probably be looking at Delta instead since North American mileage programs either have no expiration or a soft expiration that rolls every time you credit miles to the program.

Both CI and CZ are fairly expensive in terms of miles needed for Skyteam partner redemptions but if you fly enough to make their higher level elite tiers then it may still be worthwhile for the other benefits of the program. If you don't fly enough for that then I doubt either is really a great program for you.

As for Credit Cards, Amex and Citi will likely give you the most versatility with multiple airline transfer partners, but neither in HK has Delta SkyMiles as an option.