Whether you choose wood or aluminium is much about personal choice. Aluminium greenhouses are generally claimed to have less need for maintenance, but they conduct heat more quickly so the temperature range will be greater.
Condensation may form inside an aluminium greenhouse more quickly than in a wooden one. The aluminium will not rust or rot. Wooden greenhouses may require more maintenance depending on the properties of the wood. Because they are made of wood the heat transfer is slower, providing a more steady temperature.
Studies have found that a wooden greenhouse is 18% less expensive to heat when compared to a similar size in Aluminium.