Yep, the d12 is the best. In a pinch, it can also be a d2, a d3, a d4, and a d6. I remember seeing a (nearly) complete set of dice at a convention a few years ago---it was just a set of d12s with creative numbering.
I love the classic d6 (and it’s easily obtained for new players from board games etc) but the d4 is an unequalled caltrop, only matched by Lego pieces.