This program comes with all Windows PCs and is very easy to use. However, color selection is a pain, the zoom is limited, and the features are very basic.

Graphicsgale was made just for pixel art. It has a slight learning curve, but it delivers with a lot of very useful features like the rotate tool and layers.

A powerful program that offers easy image manipulation and layers. But as the name implies, it wasn't made for pixel art. It's best used for photo editing and, unlike the others, has a hefty price tag.

Paint.NET is a very versatile program which was originally intended to be an upgrade from standard Paint. It also has neat color selection options. It requires a little configuring to work perfectly for pixel art.

Basically a free version of photoshop: The trade-off is that it's more complicated and this can slow down the process significantly. It also requires some configuring to work well with pixel art.