Dear Mr. Ghasenpour, your ...

Dear Mr. Ghasenpour, your question is not very simple to answer because the selection of the best technology will depend on the quality (e.g., TDS) of the target product water quality and content of other compounds such as silica.  Overall, if the goal is to produce drinking water, then brackish water RO could still be the best technology.  If the water however contains silica over 20 mg/L and does not contain pathogens, elictrodialysis reversal or capacitive deionization may be more attractive coast-wise.  Ion exchange will only be viable if you would need to produce high purity water for boiler water applications or other industrial uses.