My scala rider (years old) that I used with my old rider 2 does not work with my new rder 500, which

aiki

is the best for me as i only need to hear the tom tom speaking ?

RoadRider

Here is the list with supported headsets;
https://uk.support.tomtom.com/app/answers/detail/a_id/25645

Many modern BT v4.2 and BT v5 headsets will work.
Its best to choose one with A2DP support for navigation instructions.