I use Photoshop Elements for any digital stuff I do. It came free with some hardware from somewhere... It doesn't have all the features of regular photoshop, but it was free, which is better than dishing out hundreds of bucks.
I use Paint Tool SAI which you can have for a free trial for a certain amount of days (30 I think) but it costs 50 USD for the full version. I'm hoping I'll get Photoshop for christmas but I really love SAI