In your shoes I would fly business class, therein lies the rub!

I started business class flying some 20 years ago when I was 22 years old. Once you start turning left, you'll never be able to turn right, at least on longer flights. So if you start flying business class at 16 you are condemned to flying it forever! It gets even worse if/when one day you find yourself in First. (Within the USA it's different as you probably know, few US airlines can match the value proposition offered by non US airlines).

It's a great way to fly, ask yourself if you're ready. Maybe you are, good luck, work hard, it will be worth every penny, and you'll love it. Maybe you're not, in which case your day will come.