#2 seems ambiguous, since it seems, at first glance, to be the derivative of the constant $f(a)$, i.e., the interpretation of #2 is usually the first interpretation in the second list in the question. #3 is the most common, and is used in almost all calculus textbooks and/or papers to denote the derivative of $f(x)$ evaluated at $a$. I would recommend #3 since that is how I have seen "the derivative of $f(x)$ evaluated at $a$" written.
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