This question is about opinions and experiences of users.

What is the best approach to align equations in order to organize common terms in a equation?

What is preferable in the particular case described below? (aligned vs array)

I have been using LaTeX for a while and always bothers me each time I use a certain command, someone says "hey, you should have used this other command". Although I like to have options, sometimes it is just not simple to find out the best option among them. In this particular case, we are talking about the package [amsmath](https://www.ctan.org/pkg/amsmath).

Both environment are inside equation in order to have only one equation number. The idea is to use the right alignment of each column, such as all constants are aligned and numbers are placed left. It produces a very neat style.

Discussion about the MWE below:

1. I had to use more `&`s in `aligned` in order to align the constants while `array` used less (`array`+1);
2. There is no need of `rcl` displacements for `aligned` while `array` needs them (`aligned`+1), but with them I can control the displacement (`array`+1);
3. `array` is the basic matrix environment, should it be used outside matrices?;
4. The space between lines in `array` is smaller than it is in `aligned`. `aligned` seems much better (`aligned`+1).

From my perspective, `aligned` is much more suitable for this kind of organization, but I don't see anything deeply wrong about `array`.

[![enter image description here](https://i.stack.imgur.com/qUMQr.png)](https://i.stack.imgur.com/qUMQr.png)

```
\documentclass{article}
\usepackage{amsmath}
\begin{document}
\begin{equation}
  \begin{aligned}
    y(x)  & = y_h(x) + y_p(x)   &   &  &       &  &   &  &       &  &   &  &    &  &     \\
    y(0)  & = y_h(0) + y_p(0)   & = &  & c_1   &  & + &  & c_2   &  & + &  & A  &  & = 2 \\
    y'(0) & = y'_h(0) + y'_p(0) & = &  & - c_1 &  & + &  & 2 c_2 &  & + &  & 3A &  & = 1
  \end{aligned}
\end{equation}
\begin{equation}
  \begin{array}{rlcrrrcrl}
    y(x)  & = y_h(x) + y_p(x)   &   &       &   &       &   &    &     \\
    y(0)  & = y_h(0) + y_p(0)   & = & c_1   & + & c_2   & + & A  & = 2 \\
    y'(0) & = y'_h(0) + y'_p(0) & = & - c_1 & + & 2 c_2 & + & 3A & = 1
  \end{array}
\end{equation}
\end{document}

```