Water is basically just water. It's whats suspended in it that needs to be determined. City water normally has chemicals added to suppress bacterial growth and good water conditioner will take care of it. May be that city water could be better if it's considered safe for human consumption. Well water isn't necassarily better. It could contain heavy metals or a myrad of other things. Some wells are perfectly safe and could even be better then the local supply water. The best thing to do is take samples of each to a laboratory and get a read out to determine for yourself which is healthier.