I'd strongly recommend the Nik Software Suite for your Mac. The only concern that I have is if Google discontinues it. However... it is arguably the single piece of software that will do more for your photos than any other application or application suite.
I bought it when it was available for Aperture, Lightroom, and Photoshop. Last time I looked it was dramatically reduced in price (I think to $150) which is an absolute bargain. I use it as a plug-in for Aperture quite a bit... and occasionally for PhotoShop.