This is an interesting page where you can look at different routes and compare the performance of different airlines.

https://www.smh.com.au/business/companies/these-are-the-worst-flights-in-australia-for-delays-and-cancellations-20180427-p4zc3d.html

Here is a screen snip showing the Sydney to Gold Coast figures for Feb. 2018.  It is interesting that Qantas is the best but Virgin and Jetstar are not all that far behind.

The Sydney to Melbourne results are similar.  I picked the Sydney to Gold Coast route as it must be a fairly busy one.