The only problem with fractal generators is that they tend to put the mountains in the middle of landmasses and you don't get something like the Andes because of that (they run down the west coast of South America). It's not a big thing but a thing nonetheless. Sure my randomness has its drawbacks as well so that's why I use the Lasso Tool (with a 50 pix feather) to pick out chunks and move them around. My method is best for creating totally random things to play with just to give you an idea of what you may want. If you already have a landmass planned and know where the mountains are then your best bet is to use the black and white airbrush to paint the difference clouds to be more precise.