I have no choice for favorable disposition of the expression "of course"

[vil]

Dear teachers,

Would you be kind enough to express your partiality for one of the following three sentences?

Of course it’s dangerous, and particularly so for you.

And I’d done my best, of course, to prevent her.

That’s important, of course.

Thank you for your efforts.

Regards,

V.

[Anglika]

Partiality in what way? They are all correct sentences, with acceptable meanings.

[Tdol]

It might depend on the degree of assumption; end placement can sometimes be used to include the listener in a more conspiratorial or superior way.

[Raymott]

It might depend on the degree of assumption; end placement can sometimes be used to include the listener in a more conspiratorial or superior way.

The way to test that scientifically would be to use controlled sentences:
Do these all have the same effect?:

And I’d done my best, of course, to prevent her.
And of course, I’d done my best to prevent her.
And I’d done my best to prevent her, of course.

I'd say it depends on the intonation in speech. In writing, the last one could appear to be an afterthought.