The main drawbacks to city water are fluctuation in water chem, fluctuation in chlorination, and increased cost of both the water and the water treatments.
Well-water *could* therefore be better than city water, but it depends on your situation. Do you know the groundwater is clean? Do you have control over the well-head area such that you can ensure that the well head doesn't receive pollution (e.g. spilled oil, fertilizers, pesticides/herbicides)?
City water could be easier because someone else is monitoring these issues and actually testing the water for contaminants on a regular basis.