For me, it depends on what type of map.. and how much detail / often I anticipate its use..
CC3- if I intend to repurpose dungeon and city type maps
Dungeon Crafter III for a quick dungeon map with just a room or two. This is very customizable and low learning curve, but has its limitations.
IF I have the time.. (hahah) I use a combo of Worldmachine and Carrara with a sprinkling of Bryce and Photoshop. This combo produces superior 3d / iso type maps, but I only do that for maps I intend to use over and over.
CC3 I won't go into since most are familiar with its capabilities.
Examples:
Dungeon Crafter - Example
World Machine Top View of a Canyon
Iso View in World Machine
3D View with Carrara
Joe over at Inkwell Ideas has Cityographer & Dungeonographer which are both fairly good with low learning curve
see here>
http://cityographer.com/
Just my 2cp
DLG