Best way to connect 2 nodes with path going around other node

Question

Imagine the following MWE:

\documentclass{article}

\usepackage{tikz}

\begin{document}
\begin{tikzpicture}

\node [draw, circle, minimum width=1cm] at (0,0)  (n1) {n1};
\node [draw, circle, minimum width=1cm] at (3,-1) (n2) {n2};
\node [draw, circle, minimum width=1cm] at (4,0)  (n3) {n3};

\path [in = 270, out = 0] (n1) edge (n3);

\end{tikzpicture}
\end{document}

How can correctly control the path to go around node n2? I know there are various methods, using an auxiliary coordinate, or with controls, but I am not sure what would give a better result.

Answer 1

Below I show two possibilities; one using the .. controls .. syntax, and the other one, using the through point style implemented in Andrew Stacey's answer to Automatically connect nodes without overlapping other nodes or connections. Deciding which one gives better results will depend on several factors (and some of them subjective ones):

\documentclass{article}
\usepackage{tikz}
\usetikzlibrary{calc}

\makeatletter
% code by Andrew Stacey: https://tex.stackexchange.com/a/27996/3954
\tikzset{
  through point/.style={
    to path={%
      \pgfextra{%
        \tikz@scan@one@point\pgfutil@firstofone(\tikztostart)\relax
        \pgfmathsetmacro{\pt@sx}{\pgf@x * 0.03514598035}%
        \pgfmathsetmacro{\pt@sy}{\pgf@y * 0.03514598035}%
        \tikz@scan@one@point\pgfutil@firstofone#1\relax
        \pgfmathsetmacro{\pt@ax}{\pgf@x * 0.03514598035 - \pt@sx}%
        \pgfmathsetmacro{\pt@ay}{\pgf@y * 0.03514598035 - \pt@sy}%
        \tikz@scan@one@point\pgfutil@firstofone(\tikztotarget)\relax
        \pgfmathsetmacro{\pt@ex}{\pgf@x * 0.03514598035 - \pt@sx}%
        \pgfmathsetmacro{\pt@ey}{\pgf@y * 0.03514598035 - \pt@sy}%
        \pgfmathsetmacro{\pt@len}{\pt@ex * \pt@ex + \pt@ey * \pt@ey}%
        \pgfmathsetmacro{\pt@t}{(\pt@ax * \pt@ex + \pt@ay * \pt@ey)/\pt@len}%
        \pgfmathsetmacro{\pt@t}{(\pt@t > .5 ? 1 - \pt@t : \pt@t)}%
        \pgfmathsetmacro{\pt@h}{(\pt@ax * \pt@ey - \pt@ay * \pt@ex)/\pt@len}%
        \pgfmathsetmacro{\pt@y}{\pt@h/(3 * \pt@t * (1 - \pt@t))}%
      }
      (\tikztostart) .. controls +(\pt@t * \pt@ex + \pt@y * \pt@ey, \pt@t * \pt@ey - \pt@y * \pt@ex) and +(-\pt@t * \pt@ex + \pt@y * \pt@ey, -\pt@t * \pt@ey - \pt@y * \pt@ex) .. (\tikztotarget)
    }
  }
}

\makeatother


\begin{document}

\begin{tikzpicture}
\node [draw, circle, minimum width=1cm] at (0,0)  (n1) {n1};
\node [draw, circle, minimum width=1cm] at (3,-1) (n2) {n2};
\node [draw, circle, minimum width=1cm] at (4,0)  (n3) {n3};
\path [through point=(n2.east)] (n1) edge (n3);
\begin{scope}[xshift=6cm]
\node [draw, circle, minimum width=1cm] at (0,0)  (n1) {n1};
\node [draw, circle, minimum width=1cm] at (3,-1) (n2) {n2};
\node [draw, circle, minimum width=1cm] at (4,0)  (n3) {n3};
\draw (n1) .. controls ([yshift=-13pt]n2.south west) and ([yshift=-33pt]n2.south east) .. (n3);
\end{scope}
\end{tikzpicture}

\end{document}