Table salt comes in two forms with anti caking agents in both and iodine in one of the two.
Neither the anti-caking agents nor the iodine are toxic in the trace amounts used.
Aquarium salt Aquarium Pharmaceuticals brand contains six different salts and iodine but no mineral content sufficient to increase the GH,PH or KH.
Aquarium Salt Jungle Brand is pure sodium chloride with nothing else added. No iodine or anticaking agents.
Ocean mix is manufactured to duplicate all the trace elements of salt water. It does increase the PH, GH, and KH and contains all the salts, iodine and even some gold usually.
Cichlid salts are generally a mix of sodium chloride and Epsom for the magnesium.
Which salt to use?
For ick, any of them except Aquarium Pharmaceuticals brand should be sufficient for ick elimination in normal dosage amounts.
If you have hard water fish or brackish and want to increase the hardness as well as the PH and salt content then Ocean Mix is ideal.
If you have soft water fish and don't want to increase the hardness then any of the others mentioned will do that.
Personal preference takes care of the rest.
If you're going to use it for short-term medical purposes it makes little difference, which you use, except for the ocean mix that can affect the waters parameters.
If you want more than just sodium chloride but no water chemistry increases then the Aquarium Pharmaceuticals brand gives you six bullets in the gun since you're hunting blindly anyway increasing the odds of actually hitting something.
Long-term use of iodized table salt can lead to increases in algae production from the iodine. If that's a problem skip it.
If you're paranoid about the anti caking agents and iodine anyway then Jungles salt will fill the desire for sodium chloride without the extras.
Whether you do or don't use it for any reason at all is a personal decision you make in the privacy of your home and will never be universally accepted as the only way to go by all. Mainly because we all have different water chemistry, needs and desires.