The Fountainhead is a vastly superior effort to Atlas, IMHO. The ending of Atlas was just so bizarre and ultimately completely unbelievable that it lessened the entire book.
The characters in Fountainhead are so memorable. The Roark-Dominique relationship is truly incredible and powerful. They waited years! Compared to the force fed John Galt-Dagny Taggart relationship. Ellworth Toohey is one of the most brilliant characters ever put on paper. And it's so hard not to feel ashamed for Peter Keeting. The scene where Toohey is brow beating Keeting is the only time I ever screamed at a book. Literally screaming for Keeting to say something to Toohey, stand up for himself. But you could feel him shrinking as a man. Powerful stuff.
It so thoroughly and perfectly stated her philosophy of Objectivism. If I could read one book and one book only ever again for the rest of my life, it would be The Fountainhead.