I’ve been using KiCAD professionally as a contractor. I am still at 4.0.7 because my workload has not allowed me yet to upgrade to KiCAD5. Yes, KiCAD’s user interface a bit quirky, but KiCAD works. I also want to stress that, because KiCAD is open source, there is extensive third-party support for it.
I use KiCAD in combination with FreeCAD, an open-source mechanical package. Again, since FreeCAD is open source, it enjoys extensive third-party support. People have been able to “marry” these two great pieces of software with scripts like StepUP (in FreeCAD), which makes 3D modeling of a pcb and its components a breeze. (This can be important, for example, when you need to know the pcb will fit in an existing system.) Others have been able to even run in FreeCAD thermal simulations of a populated pcb, which was imported from KiCAD into FreeCAD.
I have done work with recently-released camera chips; that requires handling multi-Gbps data rates but also very precise placement of certain components (the camera chip is the most obvious one, but also connectors, which define the relative position of pcbs) to statisfy the optical requirements of the system. The combination of KiCAD and FreeCAD with the the third-party support like StepUP (hats off to Maui!) have proven a very effective tool. Another script that greatly helps is the KiCost script, which looks at the BOM file from KiCAD, scrapes distributors’ web sites, and compiles a BOM in a spreadsheet, which you can then copy and paste in the ordering page that accepts text entry. (I have done it on the Digikey site; it saved me quite a bit of time vs. entering each component separately in the order.)
I have also used OrCAD, up to version 16.3 I think. I found it to be very buggy and unstable. In fact, I’ve heard people call it “OrCRAP” and I agree with them. At the moment, I think the only thing KiCAD is not good at is library management. It would be nice to have a data base with actual component values so when I need, say, a 10k 0402 resistor, I can just pull it from the database with all fields appropriately filled. There have been efforts to address this.
Here are some pertinent URLs which describe some of the third-party scripts for KiCAD. The information may be a bit dated, but is still very relevant:
https://hackaday.com/2015/12/05/kicad-utilities-generate-parts-track-costs/ (KiCost, KiPart)
https://hackaday.com/2018/02/10/whats-coming-in-kicad-version-5/ (Extras of KiCAD5, including importing Eagle files)
These days, Digikey, UltraLibrarian, and snapEDA directly support KiCAD among the “big boys.”
NB. Some people confuse “Free” with “Open Source.” These two are not identical. Somebody may write code and post it for free, perhaps with a disclaimer not to be sued for damages. On the other hand, an open-source program can enforce quality standards and obligate the inclusion of the source code, depending on the open-source license. A complex program like KiCAD is not necessarily free because it has a steep learning curve and time is money.