Question

Where will the major resonance structure have the formal charges?

Answer 1

Distributed around the resonance structure. It probably resides on the most electronegative atom.

Explanation:

For sulfate dianion, we have a Lewis structure of `(O=)_2S(-O^-)_2`; a Lewis structure of `S^(2+)(-O^-)_4` is arguable, but you are not likely to see same in a text book. The negative charge is conceived to lie on the most electronegative atom, which here of course is oxygen.

For neutral structures, e.g. the bent ozone molecule, again the position of the negative and positive charges are academic, i.e. `O=O^(+)-O^-`. We try to represent a reasonable bonding formalism to account for electron distribution in the molecule. Most of the time we can do this, and such formalism allows prediction of molecular geometry by `"VSEPR"`.

See here for another treatment.