yes, welcome to the forum!
i also do enjoy these sorts of 'sliding door' sorts of questions.
i guess my first question would be are any of the current drivers brave enough to dive anything built pre 2000? endurance may have been a real problem for the younger drivers.
Hamilton VS Alonso in that Mclaren would have been as explosive as Senna VS Prost...possibly even more so if thats possible.
but when did Falvio take over Benetton though? if he was in charge in 89, i would suggest that Alonso would have been driving that car.