I usually go with whichever airline has the cheapest fare out of Virgin and QANTAS.
Getting fed is nice (QANTAS) but not essential and then i usually buy the muffins on Virgin. Their white chocolate and macadamia muffin was a treat!
I have not flown Jetstar. Probably would only would if their fares were heaps cheaper than the others. For example, Jetstar to Japan with the current cheap fares they are offering. actually, if you are looking to buy new photographic equipment (lens, etc.) then a for the same price overall you could fly to Japan, buy the gear and have a holiday!