I use Ultra Fractal to create all my fractals except flame fractals. It is a wonderful tool that provides me access to many fractal formulas and coloring forumlas, has good tools for creating and manipulating color palettes, can handle multiple layers, can integrate photos and can create animations. There is also a large user community that provides many more fractal and coloring formulas.

Ultra Fractal is commercial which is one reason it is so well developed. However, you can download a free trial version to has all the features available. Even if you decide to buy Ultra Fractal it is priced very reasonably. The creative version is only $49.

You can download the software at ultrafractal.com.