Originally Posted by BDMJ
Bikes are fun period. There are advantages to both sorts of bikes too. Finally, in almost every case the rider is the limiting factor for performance.
Light bikes require a lot less work to flick over in a turn, handle rough and loose surfaces better, and are much less tiring to ride aggressively. They also get blown around by the wind and are less comfortable for extended straight line riding.
Big bikes are fun to pull out of a corner on the gas, can be ridden in a "point and shoot" style, and flat out amaze with their acceleration. However they really punish poor riding and can be incredibly tiring when ridden hard.
After taking my big bike to the track, I realized that I just wasn't going to have the same sort of fun on the street on that bike. So, I have plenty of fun on and off-road on my little bike. I can push the bike hard at legal speeds, which is what entertains me.
In short, figure out your priorities and how much you are willing to compromise them (or buy more than one bike).
About 25 years ago I was reading an article in a motorcycle magazine. The writer mentioned an old man in Italy who was riding by on an ancient Vespa in a beautiful Italian city, making the assumption they had grown old together. Now I am 60, and maybe in ten years I will still be riding an ancient scooter. My younger brother offered me the use of his 1500cc HD tourer to keep it in use while he recovered from an injury. I tried it on a short run up a gravel town road, managed to turn it around in a wide place and almost lost it on a wet spot. The pressure on my leg was intense. I have missed the boat on large motorcycles, it seems.