I use GIMP now, but I would have to say Photoshop is the best. Mostly because I started on Photoshop then lost the computer that Photoshop was on and download GIMP about 3 to 4 months back. I have a hard time with GIMP since I know more about how to make stuff look nicer in Photoshop. That how come all my graphics so far has suck.
I don't do graphics anymore! Leave me alone about it!