I hate backticks. They have no place in modern shell programming. Here is a couple of reasons why this is the case.

Not nestable

backticks, by their nature, are not nestable. You can not have a command expansion inside another with back ticks.

command `foo ` bar ` baz`

Should the shell expand foo and baz or bar and then foo <output of bar> baz? As it happens it will run the first one. Using the modern command expansion syntax you can write:

command $(foo $( bar ) baz)
command $(foo ) bar $( baz)

Backticks are invisible

The backtick symbol is too small and too easily confused with a single quote to be used for writing maintainable code. The alternative is significantly larger and therefore more obvious.

ls "'`!!`'"
ls "'$(!!)'"

Here is a zoomed version of the line above in my terminal:

Please consider using the bracketed version of command expansion rather than backticks and make the world a nicer place