3 days in HK: to go Ocean Park/shopping/Macau, which card prefer to buy include to/from airport

If you will use MTR most and also Airport Express, Airport Express Travel Pass is recommended to you, which can be used on MTR for 3 day unlimited travel and one/two journey(s) on the express train.

However, due to your purpose in HK, I suggest you buy an Standard Ocotopus Card, which can be used on MTR, bus and Airport Express with certain discounts.