I really can’t say enough about Pyxel Edit. I really enjoy the interface for small artwork and animations. The feature I really LOVE is the color selection tool. It is really a great assistant and time saver. I disliked on other tools trying to find a nice shade or lighting alternative for shadows and highlights. The color selection and alternatives for shading, lightness, saturation, hue are great.
The tool supports onion skinning and animations. The tool is a great compliment to any game development using pixel art.
A small example of an animation of mine.