Welcome to the forum.
Have you done any searches on Perth or Adelaide on this forum? If not try doing that since discussions of Perth and Adelaide have come up before.
Also think about temperatures, where you like to travel to etc. when making up your mind. We visited Perth before we decided to move to the Limestone Coast (SE South Australia) because for us Perth was too hot, but it may not be too hot for you. We also like visiting other areas so Perth felt too remote for us.
Have a look at those other posts and then see if you have any more questions about the areas....