Most printing companies and large graphic companies use Photoshop instead of GIMP, and if you're planning on working with them (for example to have some company printing your works or selling your artwork to other companies),
That's incorrect. The printing industry favours vector programs, which means it uses Adobe Illustrator for its printing needs, not Photoshop. GIMP has nothing to do with printing, and neither does Photoshop.
As for the discussion, I can't give an accurate opinion, since I've only ever tried out GIMP once. Which ever program you're used to will suit you the most, of course. But once you get used to all of the options in Photoshop and add them to your workflow, it'll go by soooo much easier. The warp option for example, is not included in GIMP (they have a tool called the warp tool, which is the equivalent of the liquefy tool in Photoshop, but not the same thing), and it's very useful for quick short cuts. The layer styles are also plentiful in Photoshop, which is lacking in GIMP, and I use them extensively. Of course you probably won't ever touch those layer styles if you're not into; logos/text and graphic design in general.
I've had a lot of people watch my streams where I'm drawing tilesets, and they are amazed and/or confused by what I'm doing, since they've never seen that certain option or tool being used in that way. But one thing is for sure; it speeds up my work flow tremendously.
So basically, stick with GIMP if you want to be cheap, and are not planning on using it extensively. If you're an artist who draws every day, definitely go for Photoshop.