It's a matter of personal taste in which type frctal you prefer. There are mny different fractal applications around now days. As far as ease of operation and learning curve IMO I would say Apophysis and Mandelbulb3D are the easiest to learn and get amazing results from almost immediately. Apophysis because of the unrivaled support offered here at dA with Tutorials, scripts, plugins etc. Mandelbulb3D has support in a different way, tutorials are available here but many MB3D artists, like myself, post the parameters for their work with the image which allows you to see exactly what was done to achieve those results and gives a good starting point for further explorations.