What actually takes more courage, asking a question or sharing an opinion?

In my experience, both take a great deal of courage.

Giving you true opinion
It shows people who you are

I think a little of both for me

Giving your true opinion. Especially here.

Questions definitely. Especially when the subject something other consider to be unquestionable.

Neither. Making a statement takes the most courage

sticking your head in a hungry lion's mouth

Expressing an opinion will lead nowhere, because people tend to see opinions as irrelevant and insignificant anyway ("it's only her opinion"), whereas asking questions may irritate people.

depends on what the question or opinion might be

Probably asking a question.

That's often enough to attract derision and antagonise a responder.