I have a switch statement

    switch ( $id ) {
        case 'abc':    return 'Animal';
        case 'xyz':    return 'Human';
                    //many more
                    }

I am returning class names,and use them to call some of their static functions using call_user_func(). Instead I can also create a object of that class, return that and then call the static function from that object as $object::method($param)

    switch ( $id ) {
        case 'abc':    return new Animal;
        case 'xyz':    return new Human;
                    //many more
                    }

Which way is efficient? To make this question broader : I have classes that have mostly all static methods right now, putting them into classes is kind of a grouping idea here (for example the DB table structure of Animal is given by class Animal and so for Human class). I need to access many functions from these classes so the switch needs to give me access to the class