Opinion of vs. Opinion About and Opinion on

The noun opinion can take different prepositions depending on its contextual meaning. However, it should not be used with the preposition toward:

negative opinion toward him
strong opinion toward that issue

To refer to one’s attitude toward people or their behavior, the preferred idiom in standard English is opinion of:

very low opinion of that sort of behavior
hopelessly biased opinion of him

To refer to one’s views about an issue, use opinion about (or with key words like issue or question, opinion on is also acceptable):

opinion about the judge’s decision
opinion about immigration
strong opinions on that issue