What is the correct way to center \tikzpicture?

Question

What is the correct way to cause a \tikzpicture to be centered, using LaTeX? By default it appears to be aligned with the left margin.

Answer 1

\hbox to \hsize{\hfil{Anything}\hfil}

Answer 2

\begin{figure}[!h]
\centering
\tikz
\end{figure}

Answer 3

When the picture doesn't need to be put in a figure (i.e. when it doesn't need a caption), I use

\begin{center}
 \begin{tikzpicture}
  ....
 \end{tikzpicture}
\end{center}