As far as measurement systems go, Metric vs US/Imperial I think its just a matter of what you're used to. I was in the third grade when the switch was made and thus learned metric, as mandated by the school curriculums, while learning the imperial measurements on the side. I do tend to think of myself in terms of feet, inches and pounds but things like distance and speed is in km or kph to me. My career has been in the oil & gas sector and its a hybrid of measurements: reports for regulatory bodies are all in metric, where as if the company you are working for is US based, they think of things converted. Pressures, volumes, temperatures end up converting back and forth.
Personally I think the metric system IS better in many ways: everything is a multiple of 10 so its a matter of just moving the decimal point vs a bunch of seemingly arbitrary numbers.
examples
1000 mL = 1 litre, 1000L = 1 cubic metre vs pints and quarts per gallon (and US and Imperial gallons are different sizes) and gallons per barrel
1000 g per kilogram vs 16 oz per pound
100 cm per metre vs 12 inches per foot and 3 feet per yard
0 degrees C = 32 F = waters freezing point, 100 degrees C = 212 F = water's boiling point
Metric is much simpler for working calculations. For things like buying groceries, its just a function of what you're used to visualizing.