The closer the actual fan or blower is to the ear, the "noisier" it is going to seem. The slower blower is definitely going to be quieter than the high-speed fan, and even blade types and materials can help make a difference. An in-line blower/fan located a distance away from the ceiling intake can be the quietest while still maintaining a certain flow, and I have heard insulated, flexible ducting can help reduce the sound that telegraphs back to the intake. However, and especially for dryer vents, smooth walls inside the ducting can be crucial to avoding the accumulation of condensation.
Are we over-thinking this? In my own case, and with a total of three new bathrooms to eventually complete here, I just quit thinking about it and bought some relatively inexpensive Marleys with 70 cfm fans that run around 3 sones ... about the same as my tinitis, I believe!