It always depends which fuel station you go to. I for one have chosen Total. Never had any knocking issues in my 8th gen for years now. Have taken the car up and down Karachi-Islamabad several times and filling the tank up only at total has never given me a single knock.
I beg to differ on the PSO part, I consider them to have one of the worst quality fuel available. That's what I believe, could be true, could not be but my other cars have always had knocking issues with PSO fuel so I have never been to one after that. Family members with the cars are strictly not allowed to fill the fuel from any PSO station ever, Total/Caltex is the first choice and then a distant second is Shell.