Illustrator and photoshop are pretty cool, corel draw is another good one, if you dont want to spend money, try gimp, its a program similar to photoshop, but obviously not as good since its free, type it down in google and you should be able to download easily.
If you want vector graphics that Illustrator but if you dont care about vector than photoshop is the best option It just depends on you that how well you are comfortable with the software of your choice!