I'm pretty much OK with either system, though as
@IronWing says actual science uses metric, for, I think, good reasons. Human weight is in stone/lbs and height in feet/inches (until you have a hospital appt, when it confusingly all goes metric), everything else is weighed in Kg/g, as
@WelshBloke said.
Long distances are in miles, short ones in m/cm, and the only way I ever remember how many yards are in a mile is by converting from yards to feet to inches to cm to meters to km to miles (because the yard/mile relation only makes any sense if you remember what a furlong is, which nobody not involved in horse racing does).
I make an exception for Farenheit, which is the Devil's unit (used by all the thermometers in hell) and which means nothing to me without doing the conversion. It's a good way of telling that someone is either a boomer or an American if they use Farenheit (and hence to be shunned by all right-thinking folk).