If you're looking for the opposite in terms of emotional effect:
* Compliment: A positive statement about someone's qualities or actions.
* Kindness: A gentle and caring attitude towards someone.
* Encouragement: Words or actions that inspire confidence and motivate someone.
If you're looking for the opposite in terms of linguistic function:
* Praise: To express approval or admiration.
* Appreciation: To acknowledge and value someone or something.
* Affirmation: A statement confirming the value or worth of someone or something.
If you're looking for the opposite in terms of social impact:
* Respect: To regard someone with admiration and esteem.
* Acceptance: To acknowledge someone's presence and worth without judgment.
* Inclusion: To make someone feel welcomed and valued as a member of a group.
The best opposite for "insult" will depend on the specific context and the desired effect.