I built my volume business around an Aperture workflow and and taught Aperture for 5 years. I mourned its passing. But I also found I couldn't rely on it in my business when I transitioned into El Capitan. I have found quirks and bugs across numerous machines while teaching it in a Yosemite lab. It's time is ending and it's not going to get any better. If I could be happy with an older OS, I might rely on it longer. I just love the new stuff Apple keeps coming up with. 

I own and have worked with several tools including DxO, Lr, and C1. Yes, C1 has some quirks and the interface does not have the elegance that I grew accustomed to in Aperture. But C1 has given me the best fit to what I really loved about Aperture. It has additional tools and constantly gains new capabilities I would have loved to have had in Aperture. I'm not needing to rely on specialized external software as much as I might have in the past. C1 is a pretty complete package for the photographer.

Your mileage may vary. But after kicking the tires on all the others, I believe C1 is the best match for the Aperture refugee. I pay for Lr each month but that and and a lot of time spent with it still can't convince me to like it. I can rebuild my business workflow around C1 and it is a pleasure to work with and teach. With the latest 9.1 version, I'm wondering if I will need a Ps subscription for my photo work beyond the next year. And I just love the way C1 makes my images look, whether for my personal stuff or for my customers. That's my fuss… ;)

I find the quality of the results in C1 superior to Aperture and to LR, and I find the interface much more to my liking. I have an issue with slow startup for large catalogs that reside on external HDDs, and I am working with PhaseOne to see if that can be improved. We can't be expected to always store our catalogs in an internal SSD drive. I also like all of the tools available to me in C1. I never had to leave the app. My personal philosophy is to keep all my edits as close to the source as possible. I don't like having to generate RGB files that I have to store separately, even if they have smart layers like Photoshop offers for RAW files. I would prefer to have all my adjustments inside the primary catalog and be able to generate my desired output from there. C1 provides that. LR comes close, but the interface of LR is more clunky to me and I hate the slowness of the module switching interface. While C1 loads slowly, once loaded all of the tools work fast and switching between tool tabs is equally instant (like Aperture's fast switching between the Inspector panels).