Two day stay in Hong kong

What transportation cards should we by. We arrive by air around 1200 on a Friday and leave by air 1100 on Sunday. We are staying at the Butterfly on Wellington. Need round trip tickets on Airport express and we will use public transportation on HK Island and Kowloon for about 48 hours. Octopus Card, Airport Express Travel Card, or Airport Express Tickets and 2 one day tourist passes?