For bathing I recommend you to try himalayan salt; I used to have a skin reaction on Sea Salt s in my bath tub, but never to the himalayan. ( And the bromine content in this salt is like seawater was 150.000 years ago.)
But; Salts from the Dead sea are known to be very beneficial for joints and skin, and are quite high in bromine; so..whats the best I dont know; for me it has been the himalayan.