If by conventional 5W-30, you mean non-full synthetic, then the best are the semi-synthetics like red bottle Valvoline MaxLife, Castrol Magnatec or Pennzoil Gold 5W-30. They have lower Noack volatility and reach higher specs like Dexos1.
If you want an all Group 2 oil in 30 grade, then the best should be a 10W-30 that has a lot less polymer VII load than a 5W-30 would have.
You know, I can't name one conventional 5W-30 that is sold in Australia, they are all either conventional 10W-30 like GTX, or semi-synthetic 5W-30 like Magnatec.
Myself ? I use a semi-synthetic 10W-30 that is SN and A3/B4.