I've always used the software that comes with the camera, with an ancient copy of Photoshop Elements 6 for tweaks. People complain about Canon DPP but it's quick and intuitive. Silkypix is slow but gets the job done. Gimp looked like the labyrinth when I looked a few weeks ago, after a day staring at the screen I gave up. Rawtherapee is intuitive, and while I'm not a fan of pre-sets it has some of the most film-like around.
Perhaps my needs are fewer, and folks working in multiple layers or on thousands of wedding photos need the latest PS. Even freeware blows my mind at its creative potential.