Sadly, it has to be the metric system. It is simple, repeatable, precise and based on a sensible number – 10. The imperial system, particularly as applied by the British, is just a little bit complex.
In the metric system there is a base unit, for distance this is the metre. Then you can have larger or smaller units based on that for convenience : the kilometre (1000 metres each) is handy for distances between towns and the millimetre (1000 to each metre) is handy for measuring small things like, um, grains of rice. You know, if you do that a lot.
In the imperial system it just isn’t so straight forward. You might measure rice in inches, but if you put 4 together you get a “hand”. 12 make a “foot”. Three feet make a yard. Twenty two yards make a “chain” (the length of a cricket pitch by the way). Of course there are 4 rods to a chain which makes each of them, um… And 40 rods is a furlong and, well, you get the idea.
The difficulty lies in switching between the two systems. Try as people might, it takes a very long time to change habits. The Conduit‘s best friend is 5’ 10″ (that’s five feet and ten inches tall) but has no idea how tall he is in metres, despite that being the official measure of his country. He buys his beer in pints but his milk in litres (unless it comes in glass bottles in which case it still comes in pints). He tells you how hot it is in Fahrenheit but how cold it is in Celsius : confusing times.
So in summary, the metric system rules in terms of usability – it is logical and easy to grasp. However the old-fashioned measures have a charm about them which you just can’t get with uniformity. I doubt many people know what they measure in Barleycorns but if you live in the UK or the US you probably know at least one thing that you measure in that unit. Which is nice.