The best way to display taxonomies

This has been already answered here

Both the loops needs to exist and you can display it however you like.

foreach( get_terms( 'products-category', array( 'hide_empty' => false, 'parent' => 0 ) ) as $parent_term ) {
  // display top level term name
  echo $parent_term->name . '<br>';

  foreach( get_terms( 'products-category', array( 'hide_empty' => false, 'parent' => $parent_term->term_id ) ) as $child_term ) {
    // display name of all childs of the parent term
    echo $child_term->name . '<br>';
  }

}