Tough question without a good answer. I would say that CC3 is the best of the best, but then it suffers from being expensive, can be difficult to learn, and consuming more time to GET the better results. I have stated in the past that CC is what you use when drawing the maps is in itself a hobby, and in any case the results you get out are quite proportional to the time you can put into them. But then I never use anything else so I can't comment much on other systems.
It does depend on what you want out your mapping software - speed, ease of use, detail and color, practicality, etc. And are you talking about campaign maps, tactical maps for combat, city maps, all the above? Dunjinni may do great tactical maps but I don't know that it can do much if anything for city maps or campaign-scale maps. Have to let a Dundjinni user tell you that.
Really, there's probably no substitute for simply getting hands-on experience with any mapping software you have an interest in to evaluate whether its right for you. That tends to mean that you need to go to one or more larger conventions where the company concerned will be running demonstrations, or find local users who will let you play with it a bit.
I have absolutely NO idea what DDI has in store for mapping, but I wouldn't hold my breath while waiting. If it were going to be some kind of wonderful we'd have actually heard something about it, ahm-a-thinkin.