A cheap and cheerful one for years, something like this....
https://www.screwfix.com/p/bwt-wate...gclsrc=aw.ds&dclid=CLCkrP6h2toCFYcx0wodOgkP8w
Does what it says, reduces chlorine odour, limescale, tea scum.
You can get better quality self cutting taps/valves if the ones included in filter kits don't fill you with confidence...
https://www.screwfix.com/p/self-cutting-tap-15mm-x/21250