Please recommend a bathroom extractor fan

Hi All,

I need to change the extractor fan in the bathroom. It is about 3 years old, has gradually gotten noisier and is not performing as it once did.
I believe it fits onto a standard 100mm stainless tube to the outside.
I would like one that is both quiet and with good airflow. Standard sized bathroom. Currently wired up to turn on when the light is switched on, with a delay once they are turned off.
Happy to go up to £100 or maybe a little above for a good fan.
Many thanks.

 

Probably should have mentioned it is wall mounted on an outside wall, so only short ducting.