Linux

Backticks are not very distinct, as they can be confused with single quotes (depending on the font). Also $() shows the beginning and end of the command very clearly. This is even more important when you have multiple of them in some variable in example. Not to mention that you can nest $(), but that is something I personally don't like to do anyway.

There are some functional differences too: https://www.gnu.org/software/bash/manual/html_node/Command-Substitution.html , such as that backtick command set as an alias in your bashrc will be executed once on load. While $() version is executed every time you execute the alias. Also backslash is literal in the backtick variants (with exception). All in all I never use backtick command substitution; it's confusing, limited and deprecated.