The British one is the way to go because you actually get a pint (16 ounces) of beer! With the American pint, it would have to be to the rim for 16 ounces!
With the head, your getting about 14 ounces.
Watch out for the places using pint glasses the same size as the 16 oz but with an extra thick glass base. Those are 14 oz to the rim so with the head, you get about 12 ounces but they price you for a "pint"!