MKS is meter kg and second.
and FPS is foot pound and second !
and I think MKS is better because it is adopted by all over the world and is fundamental unit of length mass and time. it is also the scientific units of measurement!
But the FPS is the unit adopted by only British and not widely used .
so MKS/ SI units are better !
more details .....
1) The metric system is based on powers of 10 so it is much easier to convert units, often just by moving the decimal point.
2) Once you remember the meaning of the prefixes, you can easily convert mass, volume and distance measurements. No further conversion factors need to be memorized except the specific power of 10. But for the English System you have to remember 5280 ft = 1 mile, 4 quarts = 1 gallon, 3 feet = 1 yard, 16 oz. = 1 lb, etc.
3) The metric system is a international standard used by nearly all the countries of the world. There are actually only *three* countries (i.e. United States, Liberia and Burma) that are still using the English system.