Opinion of vs. Opinion about

Opinion Of

Opinion of is the most common phrase among the three. Your opinion ofsomething is your estimation of its quality or worth. This phrase indicates how much esteem someone holds for a topic.

When using opinion of, you’d typically see an adjective before opinion. For example, “Our community has a good opinion of the city council.” The phrase opinion of indicates how the subject (our community) feels toward the object (the city council).

Opinion On

Opinion on is only moderately used. Your opinion on something describes your ideas or beliefs regarding a particular matter or topic. For example, “What’s your opinion on the new tax law?” Usually you’d use this phrase to ask for someone’s opinion on a broad topic where many different opinions can be made. It’s the phrasing that can open up debates.

Both opinion on and opinion about are similar because they refer to the qualities of a topic. The preposition onemphasizes the topic of the opinion a bit more than the opinion itself. For example, “Chris has a strong opinion on taxes.” Here, taxes is emphasized as a topic for an opinion.

Opinion About

Opinion about is the least common phrase among the three. It’s often used to express when someone doesn’t have an opinion, as in “I don’t have an opinion about this.”

The preposition aboutemphasizes the opinion itself a bit more than the topic of the opinion. “We have strong opinions about food safety,” emphasizes opinions rather than the topic of food safety.

Source
Dictionary.com