I have used gimp, elements, photomatix (for HDR), PTGUI, Aperture, iphoto, Canon DPP etc etc etc and I always come back to the Lightroom 4 + Photoshop CS6 combo. Lightroom is much more powerful than it seems at first glance and it integrates seamlessly with photoshop. I tried aperture for some time when I first started using a MAC but it doesn't have the functionality of Lightroom.

So my suggestion would be to use DPP for the moment but have a go at a trial version on Lightroom 4, if you like it then definitely purchase it. I love it.