I use 98, usually BP.

From past experience with my GTI and MPS, BP and Caltex are generally good in Brisbane (same fuel source, BP has extra 'stuff' added). Shell varied. I did try some of the others, the GTI seemed to like the Puma fuel but shortly afterwards the carbon canister and N80 had to be replaced which was possibly related. 7 Eleven/Mobil caused bad detonation. Both the GTI and MPS loved the 100 octane fuel when available (United and old Shell V-Power Racing), they had 5-10% ethanol added to help bump that octane number up.

Our cars will generally use less fuel running 98, so the extra cost at the pump is minimal at the end of the day.