My first response is not enough information.
But if I have to choose between true and false, I'll say it's true and false.
My belief in the level of validity of the sentence is irrelavent to the truth of the sentence itself. It isn't the same as, for example, "Everything I say is a lie."
The sentence "This sentence is false.", as it stands, is nuetral. The sentence cannot actively be true or false. Since there are no real facts within the sentence by which to judge the truthfulness, it becomes a matter of opinion whether the statement is true or false.