I need some wire for the mig I've purchased. I was going to go for .6 as it seems the done thing for car panels. Are any of the brands in the image worth buying
You'll just want a standard SG2 Mild steel MIG wire, 0.6 or 0.8 will be fine for car panels.. Novofil or Novo bronze in that picture will do the trick providing they're available in the size you want.
What mig have you bought? most but not all will take 5kg spools and even if they do you will often need an additional collar and spacer kit, or make up something yourself of course.