I'm going to say this, use the program you know well. If you get super used to one program, it is hard to try to transition to another...trust me, I've been using Photoshop for over 10 years and every time I try to use another program...I get frustrated because it is not Photoshop.
In the end of the day, the final product is more important than what program you used. Someone can make an amazing piece in MS Paint and someone can make the worse possible thing in the most expensive fanciest program there is.