RE: Which is better?
I've worked with both Gimp and Photoshop. If you can't afford to buy Photoshop, then go for Gimp. If you can afford Photoshop, then definitely go for Photoshop. PS comes with better Gradient Maps, has more effects, has more blending modes, has blending options, better brush options, and is easier to manage.
EDIT: For faking, PS is even better, since everything is already placed for you if you download a PSD font guide.