It depends on what look and feel you are going for and also if you feel like it's important to you that the deck material is environmentally friendly. What style do you have throughout the rest of your home?
Both hardwood timber and composite are very durable, however, you may need to maintain the timber more than the composite (Blackbutt timber may crack on the surface if not maintained properly). Timber is aesthetically pleasing and looks very natural and the composite has a more modern and stylish look and feel (new techwood is the eco-friendly alternative to natural wood).
Best material for decking
Pool Deck - wide or narrow boards
Timber for deck
Aluminium or Timber bi-fold doors for extension on heritage home?