AUSTRALIA ONLY -what brand of fuel to use?

I have a subaru impreza and have read in fhe book and on the subaru website,that not all fuel additives that petrol companies use are compatible with the subaru boxer engine. I have now moved to an area that I get the choice of Shell,Caltex,BP and Mobil. Can anyone shed any light in this. Subaru do not give any prefered brands, but they say not all are compatible. Also, my car requires 91 octane, but it will work better with 95 octane. Can I use an E10 fuel that is 94octane?