I use Paint.net to draw as well as base color. I use Photoshop to do the rest, even if I have to draw a background, I usually do it in Photoshop.
Also, I don't know what thread it was in, but I saw somebody talk crap about certain tools people use, like curvy line tools and such. I am going to respond to this here, due to the subject of this thread.. I can assure you, the tools do not make the artist. If a person sucks, they will still suck no mater what tool they use. These tools are only bad when people don't know how to use them right, or just simply are not good enough to know how to generate the shapes they are imagining. It's up to you how you create that shape, but it's only going to happen right if you are more accurate in creating what you see in your mind. It also depends on if the person is trying to take a shortcut or not.