I have and enjoy a staggering amount of Campaign Cartographer content, because they were the first gaming-dedicated mapping software I remember encountering in the ads of "Dragon" magazine, and with enough time and learning it can be used to produce amazing, professional quality maps.
What I actually end up using, though, because they take a fraction of the time but still get me 90% 'as good,' are
Wonderdraft (world/overland) and
Dungeondraft (dungeons/battlemaps). Fairly cheap, intuitive to use, and look great.