I would go for Campaign Cartographer 3 and some addons (like Dungeon Designer and City Designer). You can slap together a decent looking map in 10 minutes. Even a city.
The catch of course is that CC3 is very dependant on symbols and CC3 maps often have a generic look (which I never found to be a problem). You need to master the software to create more unique looking maps. Even then you will never achieve the freedom of graphics software like Gimp or Photoshop of course. But mastering those programs isn't easy either and you will certainly not be able to create a map right away.
That's my 2 cents, opinions on this forum may differ