I guess I like "inconvenient"
I use 12 copper pennies = 1 silver schilling, 12 silver schilling = 1 gold crown. A gold coin minted by a non-royal state is a "mark" and I have half pennies too! I vary the names of the coinage in different areas / nations. And Elves refuse to use copper coinage, the Dwarves invented that. A platinum imperial is an ancient Elvish coin (magically smelted). The dwarves use a electrum (gold and silver) half crown too... and merchant houses mint trade coins (and use letters of credit with magical watermarks). Silver is the basic monetary metal rather than gold btw, making copper useful for change and gold useful to save weight / bulk. So much fun with coins
Customizing coinage (and weights and measures) is useful for world building. And counterfeiting is a thing, with shaving drilling and debased currency thrown in as well...
I'm rambling, as usual, between grading papers sigh