Learn English – What’s an antonym for “tyranny”

Aura might work, as it has a generally positive connotation. There is also halo, though that might be a little over-the-top in this case, or the more neutral property.

Depends very much on what you mean by opposite. If you mean that I am against Bob's decision to quit his job, then GEdgar's suggestions, along with a myriad of synonyms and antonyms from thesaurus, will do

I oppose Bob's decision...

I reject Bob's decision...

However, if you mean that you are not in favor of, but not necessarily against Bob's decision, then it could be

I don't support Bob's decision...