I would buy an Ender 3 and replace the motherboard with SKR Mini E3. Its TMC2209 drivers make the steppers nearly silent.

After that the power supply fan is the loudest thing. There's no space inside for a bigger fan, but the hotend and steppers don't use a lot of power so one option is to use a fanless AC adapter, and either mains powered heat bed or masking tape/glue stick on a cold bed.