Advice on handheld shower w/dechlorinator

We are rebuilding a bathroom from the studs. I prefer a handheld shower and would like to use a dechlorinator for health reasons.

What kind of dechlorinator should I purchase?

The salesman where I bought the Delta shower controller also sold me a 90 degree wall supply elbow to come out of the wall since I wanted to put the handheld on a slide bar. I could put the dechlorinator on a regular shower head stem and attach the handheld to it or I could take braided stainless steel hose before it exits the wall and run it to a dechlorinator in the vanity located on the other side of the wall. Which would be preferable?

Thanks for the advice,
Sharon