Formal:
* Articulate: To express clearly and effectively (often implies a well-thought-out opinion).
* Advocate: To publicly support or recommend a particular cause or policy.
* Contend: To assert something as a fact or opinion, often in a debate or argument.
* Enunciate: To state clearly and precisely (emphasizes the clarity of the expression).
* Expound: To explain or discuss a topic in detail (often implies a thorough and well-supported opinion).
* Proffer: To offer (an opinion) for consideration.
Informal:
* Speak up: To express your opinion, especially when you disagree.
* Chime in: To join a conversation or debate and offer an opinion.
* Weigh in: To offer your opinion on a topic, often with authority.
* Pipe up: To speak up, often in a forceful or assertive way.
* Put in your two cents: To offer your opinion, even if it is not solicited.
* Sound off: To express your opinion forcefully and loudly.
* Give your take: To share your perspective on a topic.
Other options:
* Assert: To state something forcefully and confidently.
* Declare: To announce something publicly, often in a formal way.
* Maintain: To continue to assert an opinion, even when challenged.
* Opine: To express an opinion, often in a formal or scholarly way.
* Propose: To suggest something for consideration.
* State: To express something in a clear and direct way.
The best word to use will depend on the specific context and the tone you want to convey.