I met a girl who explained it to me like this:
If Sydney and Melbourne were two women in a bar, Sydney would be the gorgeous blonde with a breath taking figure that would put Marilyn Monroe to shame. Her external beauty allows her to soak up much of the spot light, but she lacks substance.
On the other side of the room is Mel' who would be more closely associated with the quiet brunette. More like an Audrey Hepburn, she is stunning in her own unique way. Melbourne is more likely to hold deep intimate conversations that continue late into the night.
In reality there are so many factors to consider when comparing the two its no wonder the debate has lasted as long as it has...
-The People -Lifestyle Pace -The Cafes -Public Transport
-The Culture -The Scenery -The Pubs -AFL vs NRL
...the list goes on.
What it seems to come down to is: What type of atmosphere are you looking for?
Melbourne definitely has a more laid back feel to it and the arts/entertainment culture sets it apart from most other cities in the world. The public transportation set up makes it extremely easy to navigate from one side of the city to the other. The cost of living is slightly cheaper than Sydney(both cities are terribly expensive), and overall Melbourne is an extremely livable city.
Sydney's lifestyle is noticeably more fast-paced and heavily business oriented. The views from the Harbour Bridge and of the Opera House are awe-inspiring. Sydney is also home to Bondi beach which ranks among the worlds best, and the botanical gardens within the city create a heaven amongst the high-rises.
After spending time exploring each cities gorgeous landmarks and surprise-filled lane ways, I can see why the rivalry continues. What I will say definitively is that their similarities far outweigh their differences and deciding which city is better seems to be largely subjective. If you've never been and you find yourself in the southern hemisphere, do yourself a favor and take a holiday then leave us a comment and tell us what you think!
For those of you out there who have experienced the rivalry first hand, What's your opinion?