I know I might stir up a bees’ nest here, but this sample image shows just how good Lightroom can deal with extreme lens issues while Aperture cannot. I shot this with one of my best lenses (the 35mm f/1.8 mentioned in my previous post) and it really has few optical flaws. But this subject matter shows an extreme condition (high contrast lines) where you can see much of the fringing and some chromatic aberrations. Lightroom 4 has little problem dealing with this extreme situation and the results are excellent. Aperture, on the other hand, really has no way to deal with these optical aberrations and could not produce such a clean final image.
Hopefully, someday, Apple will bring Aperture into parity with Lightroom 4, but I’d bet money against that. If so, that would be a shame. Until then, I’ll keep using Lightroom for superior processing.