[stiletto2]

CVT's are not as efficient as chain drive, but the CVT's are simpler to operate and maintain. Just guessing, but probably also cheaper per mile than chains, oil & sprockets.
In their own right, CVT's are always in the correct gear. Again maybe not always at the most efficient ratio, but close enough for the task and it is all automatically done requiring no other input than simply changing the throttle. CVT's are simple, but effective - geared transmissions with chain drive are more complex, but more efficient. Another alternative with a geared transmission is a belt driven final drive. Nearly as efficient as chain drive, but cleaner with no oily mess, low maintenance and quieter than a chain. It's all about what works best for you. BTW, for scooters, insurance is likely to be less costly as well.

Prioritize your requirements to establish positively what you desire (plus the degree of flexibility in your criteria) Then do research. Ask about what are considered quiet bikes (as you are doing here since that seems a priority) find bikes with belt drives if you would consider them acceptable, consider bikes of acceptable engine size, initial and maintenance costs and any other criteria you deem most important in your decision. Weigh your options as you find them then decide which best meets your criteria.

What ever works best for you since the "best" is subjective. Unless there is a more specific objective like the objective of simplicity; then CVT would be the choice - objective of higher efficiency; then manual or automatic geared transmission with belt or chain final drive would be a better choice.

But getting good help in your decision would be easier if we knew more of your criteria and its order of importance. That way you wouldn't need to sound snippy when someone makes a suggestion that you think irrelevant or less important and people would be less inclined to question your motives in your choices. No sense in arguing semantics of what is better for you when you could already have it laid out.

Ideally, what I would like to see is a CVT that can be operated automatically or manually... ditto for the clutch.

Anyway, I think any bike could probably be modified with some sort of noise baffling after the muffler to make it quieter than it might already be.

EDIT: OH! I see you got a bike already anyway... but already seems you are not completely happy with it... later possibly come to regret getting it & utterly despise it because it is not comfortable.