Not that this has anything to do with Stadiums, but...
The difference between cities is that the 5% of Sydney that is near the water, plus the inner west, are great, but most of Sydney is a dump. Drive anywhere else at you see run down shops and houses and everyone seems depressed. You simply don't see that in Melbourne.
I see Sydney as 10-15% rich, 20% middle class and the rest as poor. Almost all of Melbourne is middle class. There is only a handful of run down areas.
Melbourne has fewer attractions, but the suburbs of Melbourne - where people actually live, are much better. It is easy to get around, both driving and PT.
Melbourne actually has better weather, but Sydney and all of NSW has a much, much better pub culture.
Plus we can spell Gyros correctly. Yeeros?
Back to stadiums...
Melbourne wins because it has the best rectangular stadium in Australia.
Melbournians consider Etihad (Docklands) as a dump (and hate going there compared to AAMI / MCG), but if it were in Sydney it would easily be the best stadium there and everyone would rave about it.