Which is the best alternative to Photoshop?

This is the question I was keep asking myself for long time. Although photoshop is very good tool but for casual  photo editing it is very expensive. I have tried GIMP, but it is not so user friendly.

I have looked for following features.

• It should support layers. It must allow to store layers in to file also.
• Gradient and brush support.
• Most of the filters should be available.
• Easy to use.
• Cheap

After lot of research I found Paint.net is the best free alternative to Photoshop. Which photo editing software you use on daily basis as alternative to Photoshop? Please comment.