GIMP vs PhotoShop?

[Beoner]

In your case, as you already own the PS, I don't see any reason for you to use GIMP (unless you are like me and prefer the GIMP's text tool and some other stuff). But you can try using GIMP, once you know PS you'll not have problems with GIMP. About having more or less tutorials for GIMP, I think (but I'm not sure, never counted) there are more tutorials of Photoshop here in CG (over the internet it's probably much easier to find PS tutorials due to its popularity).

But PS may have some stuff GIMP doesnt (specially because its paid) so it depends on your needs. As I said before, you already own PS, you can try GIMP. If it was the opposite could be a little more difficult...

I use both PS and GIMP to do my maps (and probably I'm the only one to it, but I do that because I like somethings on PS and some on GIMP);