Why is Melbs so popular, I know its a big city but I assumed Sydney and Melbs would have similar positives and both have a lot of people trying to return home.
Yes, both have a lot of people trying to return home, but "Melbs" as you so quaintly put it has around 1/3 of the crew requirement that Sydney has, hence the wait.
There is no comparison between being based out of Melbourne compared with Sydney. Melbourne wins hands down. (I'm not talking about non-work lifestyle here.)
A quick look at the current Perth roster for FO's indicates a very laid back pattern. You wont be working very hard there, and only a few overnights per roster. Great if you like relaxing, not so great if you're building hours, consolidating your skill-set, or need the extra cash that you get from overnights.
DIVOSH!