On my forums, many times the title of a new topic is not really great, to say the least.
Or even if the title is great, the question is mainly always in the post and not the title.

That means when you are reading a topic, with a lousy title, you get to read the "best answer" before you see the question, which is in the first post.

I would suggest the "best answer"-post to be directly under the first post or even better have a setting choose above or below first post.

Agreed.

I would think under the first post would be better. Seeing it first could be more confusing than helpful if you don't know the whole problem, situation, etc.

Has anyone got a solution for this?

A hook perhaps?