Going back a few years, actually quite a few, I remember the battle royal between the Sportster, the Triumph and the Norton and who was fastest. Stock for Stock, most of the time it was who managed to get off the line first and not miss-shift, which won that particular run.
This of course was up to 1969 if I remember correctly when Kawasaki introduced that motorized pencil, the 500cc 3-cylinder, two stroke rocket the Mach I. Which was able to show the bunch of us the way of the future, usually with the front tire high in the air.
Saying that, let me say this, on a long stretch of road with a healthy cross wind that lightweight motorized pencil would be running down the road in a straight line and scraping the foot peg trying to stay upright while fighting the wind. Whilst we on our Norton's and Sportsters .. motored happily down that road.
The bottom line, IMHO, is you can build em lighter, you can build em with more cylinders, and you can build em with more horsepower, but you simply can't beat a big inch, pushrod Twin for everyday and general riding. Lord, that torque is addictive.