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I have been using this Oxo Good Grips one for years. It works perfectly and it's easy to clean.
They have to be sturdy and all metal else they're likely to snap I reckon.
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Get the Master Class one like this:
(Amazon do one)
Do not buy one that has changeable disks. Make sure you have one that is lugged on the end to allow it to sit on the pan.
[Edit]
Holy crap - this place exists: potatoricer.org.uk
Suggestions for a potato masher or ricer?