Strikeout - when which package ? ( ulem vs soul vs ...)

Question

When to use which package for strikeout?

I see answers :

\usepackage{ulem}
\sout{Hello World}

or

\usepackage{soul}
\st{Hello world}

or

\usepackage{cancel}
\cancel{Hello world}

In what situations is it best to use which one?

Maybe there are other packages I am not aware of?

Shouldn't be there one standard way to strikeout?

Answer 1

cancel is intended for indicating mathematic cancellation, and consequently only works in math mode; it also strikes out diagnoally.

soul and ulem seem pretty similar. One basic semantic difference between them is that ulem per default changes the definition of \emph{...} to underline its argument instead of putting it in italics. This seems to aim at the reproduction of typewriter typesetting, when underlining often was the only means of indicating emphasis. Since using underlining for emphasis is mostly deprecated nowadays, I've always used soul when I did need to underline something.

The one big reason in favor of soul, however, is that it's able to deal with line breaks and hyphenation:

\documentclass{article}

\textwidth=1cm % just to force hyphenation to happen

\usepackage[T1]{fontenc}

\usepackage{cancel,soul,ulem}

\begin{document}
\[
\frac{\cancel{5}*17}{\cancel{5}*23}
\]

X \sout{supercalifragilisticexpialidocious}

X \st{supercalifragilisticexpialidocious}

X \emph{supercalifragilisticexpialidocious}

X \ul{supercalifragilisticexpialidocious}
\end{document}

(The X are necessary because LaTeX won't hyphenate the first word in a paragraph.)