Hmm.
I do not live in either Melbourne or Sydney but have spent plenty of time in both, for work and leisure. I have driven extensively in both and traveled on public transport in both. In my mind, Melbourne is far easier to navigate than Sydney, in both pubic transport and for driving.
You are right in that all cities are planned. Cities expand and out grow their initial planning and sometimes, due to geographical features or other considerations, the planning that follows is not always integrated with what has come before.
Sydney was a much more organic city than Melbourne, growing out of the site of the first colony on the Australian mainland. By necessity, it was bounded by the harbour which is so integral to its character and lifeblood. Very hard to grid or plan around such a feature as this.
Melbourne was much more planned but was also easier to plan and "grid", given the nature of its site. This is why Melbourne feels so much more programmed than Sydney in its layout.
I love elements of both cities, but Melbourne for mine takes the title. There is a reason that Melbourne was name the most liveable city for 7 years in a row, from 2011 until 2017. Vienna has taken the mantle for 2018 with Melbourne 2nd. Sydney, to be fair was not that far behind, in 5th position, with Adelaide rounding out the top 10.