Fastest are generally exiting for reasons stated before (running cars to limit the whole time) and the increased corner speeds. But in the days of no chicanes and low drag config cornering was still exciting albeit slower. Even with the old WSC fuel limits it was awesome especially for the strategists out there but sometimes reduced the last hour to a procession.
For me though the whole diversity of cars and without a doubt the engines and NOISE just increase the whole excitement factor............just don't tell Ulrich Baretzky because he has most definitely got his facts on noise wrong.