I'm trying to understand if there are any benefits of using:

pushd my_dir make all # ... or something else popd 

vs

( cd my_dir make all # ... or something else ) 

or is it merely a preference thing?

I guess the latter notation can have issues like you may need to set -e (and other flags again), but it still carries out the exit code of its last command, and looks better in terms of syntax.