I have been using Aperture for about eight years. My Aperture library contains about 80,000 images. And because I bought into Apple's ecosystem, and actually like the intuitive interface, I resisted the trend of moving to Lightroom. I first tried Lightroom 4, but quickly went back to the familiar Aperture. However, that brief exposure allowed me to see some of the possibilities in Lightroom's develop module that Aperture didn't have. After Lightroom 5 was released, I bought it, but still didn't use it more than occasionally. I did end up getting a Creative Cloud subscription too.
Finally I made the move to Lightroom. Strangely it wasn't because I wanted to, but because if Aperture's constant crashing and causing my two new state of the art Macs to crash with kernel panics. This was after the update to 3.5 and 3.5.1. Communication with Aperture's engineering team didn't resolve the issue.
I traveled overseas as one of the accredited photographers covering Carnival 2014 in Port of Spain. Attempting to give Aperture one more chance, it embarrassed me. It continued to crash. I turned to Lightroom to curate the thousands of images I shot over a 3-week period. That was it.
Aperture needs a backbone rebuild. I think there may be some legacy code in the software that needs to be tossed. The software is, in my view, significantly behind in its ability to post process images from large images that are produced in cameras like my D800.
Apple has really disappointed me in their handling or lack of handling of Aperture. I won't ever out all my eggs in Apple's basket again.