If you want a silent fan, I recommend you look for DC fans.You can recognize them from having more levels (eg 20 instead of 3) besides mentioning DC somewhere. The Duux fans are really small and expensive, but they sell spare parts if you are into longevity.
I can recommend the DC variants of the Cecotech EnergySilent series if you want a normal sized standing fan from a Spanish brand that is cheaper than Duux. Their only downside is the beeping noise they make when you change the setting, as the reviews will also tell you.