Pump gas 91octane, 95 octane and 98 octane

We can notice that in the pump gas there is different fuel type 91 octane, 95 octane and 98 octane so can you tell me what is the Best Air Fuel ratio of each one or it has the same air fuel ratio 14.7:1 ?

Stoichiometric ratio stays the same between these fuels. Sometimes though under power you might choose to run a different AFR. Example under power on 91 octane you may choose to run the engine a little richer to help combustion temps and reduce chances of knock