I too am a "gimper", but not very active on it of late...

Gimp is the open source version equivalent to Photoshop. While Photoshop is the industry standard, Gimp is as capable in most things, and even better in a few others, but lacking in still others. Some of the pros here use both, believe it or not..."using the right tool for the job at hand". One BIG advantage to any non-industry user that Gimp has is that it is FREE. It should also be stated that here at the Guild there are plenty of tutorials for both of these programs, and most of them can be translated easily from one to the other.

While I agree with arsheesh on a few of his points about CC3, the end result of your map need not be as provided by one program alone. CC3 is capable of doing many different styles, sometimes depending on add-ons, but it will require some effort in learning about the programs abilities. You can also use different programs at different stages of the map and end up with something awesome.

I would agree with the suggestion of giving Gimp a try, but if you also have access to CC3, try learning that too.

I hope you enjoy your stay here at the Guild