Day 5 of the 30-day D&D Challenge: Your Favorite Die.
From a player’s point of view, I‘ve always liked the d6 best for all RPGs: easily available even in a country where RPGs are very uncommon, and since we’ve been used to them since childhood, they’re very easy to read even when the values are printed on them as pips instead of numbers. The only thing wrong with the d6 is its limited roll range, which challenges us game designers to come up with creative ways to extend it.
As favorite-die-that-was-hostile-to-me, though, you can’t beat the d20! Specially when it was in DM JJ’s hands! Those blasted icosahedrons had a way of turning up 20 whenever JJ’s orcs/ bugbears/ temple guards or whatnot were stepping up to the bat, to groans, merriment, and the terror of our characters.