I would, personally, like to see those that paid with their lives get honoured first! Sure, Mario Andretti went through a lot, but he still lives. He never was and never will be killed in a motorsport event! I'm not trying to take anything away from his achievements, he was a damn fine driver, but there are others who are far more deserving than him - Ronnie Peterson, as you mentioned, for example.
Others include the four I've already mentioned - Roland Ratzenberger, an F1 driver, Allan Simonsen, who drove at Le Mans and Bathurst, Peter Brock, who won at Bathurst NINE times and Bruce McLaren, who's name lives on with McLaren Motorsport and the car brand of the same name! I mentioned Ratzenberger only because he died the day before Senna, all the others have links to GT6 through either cars or tracks. McLaren, Bathurst, Circuit de la Sarthe and Goodwood (Bruce McLaren died at the Goodwood Circuit in 1970)! There are lots more but I couldn't stuffed looking up all the names...
So basically, what I'm talking about is driver's that leave behind a legacy, not those that are still kicking!