Is it good practice to use wpdb->query() function?

I am using custom php code to perform data insertion, deletion, updating and other tasks. I am able to insert data into a table in two different ways,

$wpdb->insert($table_name, array('id' => NULL, 'name' => '$name', 'email' => '$email', 'city' => '$city'));

and

$sql = "INSERT INTO $table_name VALUES('', '$name', '$email', '$city')";
$wpdb->query($sql);

Is it a good practice to use wpdb->query() function each time by passing my query to the function instead of using the dedicated functions like insert() and delete() etc? If not, what are the disadvantages of this approach?

If you look a bit into the source, you’ll see that $wpdb->insert() will use ->query() under the hood. So should be the same, right?

Not that simple. It doesn’t just use ->query() but also ->prepare(), which is considered best practice. Meanwhile with your code example you’ve probably just opened yourself to SQL injections.

The takeaway here: If it is a simple operation and the ->insert() etc. method work – use them. They’re tested and contain little risk. Writing your own queries always carries the risk of opening yourself up to troubles such as SQL injections.