I have mostly older shaft drive bikes. V65, Eliminator, Shadow
Also have a belt drive Raider and a chain drive ZRX I just got. First chain since about 1970 something.
I had the shaft drives first after about 5 years of no bikes. To be honest about the V65's they were never a great handling bike to begin with. To much power and too little frame. They can be a handful in the corners and you do get a lot of shaft jacking if you are not smooth with the throttle. Big time mid corner adjustments are, or can be quit interesting. (Read that as oh my God I'm gonna die down right frightening!) But, you do get used to it. Shaft drive Shadow is not near as bad, don't really notice it but not the horsepower either. Eliminator is in the middle, better handling, less power than V65
Got the Raider, I was a little afraid of how that big 210 mm tire would go around the corner, but it does corners like a race bike, compared to the Magna anyway.
ZRX is more power, chain drive and I am nowhere near finding the limits of that thing. I still go into corners with the Magna mindset and a lot slower than I could. Slowly working up to finding the edge, well maybe close enough to SEE the edge, but I am not a racer and we have pretty straight roads. Better tires and suspension also help I am sure.
What have I told you? Not much. They all have their place, good points and bad points. A lot of it probably depends on what you plan to do MAINLY with the bike. If you are buying a canyon racer, I doubt you want shaft. A big tourer, maybe not a chain. Most big V twins now have a belt, I think they have most of the bugs worked out of that. Might not want a belt on a VMax tho, personally I think the shaft is a bit out of place on that bike, a chain would get more power but it already has more than anyone can use.
You lose about 20 percent through the shaft, something less than 10 percent with a chain or belt I have been told. Put a couple shafties on the dyno last summer. HP at wheel was almost exactly 20 percent off the rated engine horsepower so I tend to think that is pretty close.