It is a bit simple for me. If you are creating images that are competing at the highest level of quality in display for very controlled lighting, with high contrast subjects, I choose C1, as I also choose a Phase One camera. If you are shooting people in action or events and outdoors and less controlled light setting, I use Lightroom, which I tend to shoot those subjects with a DSLR. So if you are using filters and such on a image, I wouldn't use C1 for that. Keep in mind, a lot of times the differences are relative to your output type and viewing distance. So the difference in many mediums and subjects is negligible. On the controlled light contrasty subjects, C1 will poke its head out and tell you A-HA!....when you are the type that always strives to do better, you do better.
I personally use LR much more often than I do C1. but I couldn't get the results of SOME files C1 can, where LR cannot (or lack of desire to try hard enough?).
So if you are in the LOVE of or in the business of making images, you will use any tool necessary to get the results you are after. That is why I have both.
Can you fillet a fish with a bread knife? Can you slice a baguette with a fillet knife? You just might, but how you do it will greatly differ....so will the results/time.
What I did learn after some use is that LR being a manager is not as bad a thing. I was very opposed to it. Now I just deal with it, as I don't have a choice. It still slows down the way I work. But it is not a deal breaker.
Since I still use a folder structure it works with it, and managing is rather smooth. Navigating between Lib mode and Dev mode is the issue it creates.
Another thing I learned is that I don't think I will ever get used to the way C1 wants to handle file "engagement". This is why you read others feedback that they loved C1 up until version4. Which I agree with. This is coming from someone who used C1 much before LR(not to mention my C1Universty classes/testing). It is mentioned often that you don't have to use the catalog feature, but it makes little difference, you still have to deal with a Session feature that you can't disable, as it is part of the entire file "engagement" system. So you're really never browsing. You need to be in a Session, then browse. Of course this is not likely to change soon.
Another draw back for me is that it creates a set of folders in throughout the drives and folder that you pull up an image from. So if you like managing your folders in some hierarchical structure, you will have a bunch of C1 and subfolders throughout your file system. What I have been forced to do is to shoot in a Temporary (MyPictures on C) location. Edit the files in this location, then move everything to the servers...and other variations of this from suggestions(which works sometimes). Keep in mind, if you have a single drive for your images and your not dealing with many of them , this really might not be an issue. It was a major issue for me to use C1 as a "when in need" application. One other thing C1 does is take time to populate the folder you are in. It will take a bit then start adding a bunch then slow down on the end(this will vary based on your image location and connection to that drive). This I would deal with if it was a non-Session browser way of working. The other thing is the way the tool buttons and all the GUI is laid out. It doesn't conform to Windows or iOS of standards, so if you are not using the software for 4-8 hours a day everyday, it is easy to forget how things work, and you can easily get frustrated with it when you have deadlines to meet. This maybe personal, but many have voiced this struggle. One other thing is that you can ONLY shoot PhaseOne backs/camera tethered only to C1. Only LR and C1 can process IIQ files.... so you will need it if you ever go that route. That is all the ugly for me. The rest is beauty....
Other than the above, which I know is a good chunk..... I have only good to great things to say about C1 and the files I get out of it. I know what my eyes know and what my experience of 20 years can see, therefore I have C1 in my top drawer arsenal.