Aldi is consistently cheapest but with lower choice. If you are flexible with what you want, go to Aldi. Sometimes you'll try something new and like it. However, of you have favoured brands or things you like, you pay a premium elsewhere.
Aldi has great quality meat and vegetables. But limited choice, just like everything else there. I do most of my shopping there and supplement with IGA for the things I can't get.
Harris farms is also good quality but expensive. Cole's and wwolies are generally best range but not always the freshest. They are middle of the road pricing.
Generally I avoid them where possible as they actively distort the market and are bad for consumers.