Ahhhh! The Honda 6 wins hands down for me. There will be/has been nothing quite like it. I was lucky enough to be at the bottom of Baaregarrow in 1966 when Mike Hailwood and Stuart Graham came through on their 250 sixes. OH MY GOD!!! Nothing compares.
And this year I was lucky enough to catch up with Stuart on the 6 just after Alpine on Friday's Parade of Champions, and for a few moments I followed him just soaking it all up. some of the old bikes look like dinosaurs, but not the 6. I still think it looks fabulous 40years later!
As mentioned by Sticky, today's fans are missing something with the "synthetic shrink wrapped" sounds of the modern day Japanese four cylinder. Even my old factory RC30 sounds a bit special because it is so different.