Sentence parts, usually verbs, are often omitted in comparisons beginning with than or as. To test for the correct pronoun, mentally complete the sentence.
They is the subject of the verb are, which is understood: Norman is much better off than they [are]. If the correct English seems too formal, you can add the verb.
This sentence means that we respected no other candidate as much as we respected her. Her is the direct object of the understood verb respected.
Exercises:
Pronoun case (such as I vs. me) 1
Pronoun case (such as I vs. me) 2
Pronoun case (such as I vs. me) 3
Pronoun case: review 1
Pronoun case: review 2