Just like so many here, I started out with FE, but rarely use it any more. 90% of my time is spent with XD; I love being able to make 3D fractals. For that same reason, I seem to have most of the programs that will do quaternions, including the entire suite from Mystic Fractals. Not that I really know how to use them, of course. When I want to do bright fun colorful images, I use MBF. I tried UF but didn't like the UI, and I've never been that big a fan of flames; whenever I get the urge, I can do them in XD.