> Even the good old GDP per capita covers your case.

GDP or even GDP per capita is not the best metric. You can sell 100 iphones for $1000 or sell 500 cheap androids for $200 and both countries will have same GDP but I think output and outcome is much better in latter case (you produced 5x more products and 5x more people can benefits and be more productive with those 'tools'). Sure iphone for $1000 is better than $200 android phone but is it 5x better? Same with cars you can sell ferrari or more cheaper toyotas for the same value. We would have to measure how much goods we can produce.