Out of curiosity I decided to purchase a Nikon camera and see how the experience compared to my Pentax KP and plethora of lenses.
I was able to find a Nikon D5300 reasonable cheap that I purchased. I knew that I could not use older AF lenses on my D5300 except in manual mode which somewhat bothered me. I do not have that worry with Pentax screw drive lenses. I know that a D7xxx series camera would solve that problem but more on that later.
The first thing I discovered is LBA is common across platforms. After a couple of months, I found myself with an AF-S 18-105mm, AF-P 70-300mm, AF-S 40mm micro, AF-S 18-55mm, and Sigma 17-50mm F2.8. After the intuitive and easy Pentax interface, I found that I am not a big fan of Nikon interface. It takes too long to change ISO and the flash settings are buried in the menu. Since light setting are important, I find it much easier to change my Pentax settings. On the flip side the Nikon autofocus was very snappy and I was pleased with the rate that I could focus and pull off shots on moving targets like the red shouldered Hawk in the picture.
Researching Nikon lenses, I kept seeing all these nice screw drive lenses that I wanted to try. So, I ended up adding an affordable D7000 to the collection. With this came more lenses in the form of a Sigma 135-400mm and a Sigma 70-210mm F2.8. Both these are screw drive and do not have Vibration reduction. Here is where I found out how spoiled I am from the Shake Reduction in my Pentax cameras. Without shake reduction in the body or lens you have to be uber sensitive to either keeping the camera still or bumping up your ISO to keep the shutter speed super high. Since one of my preferred subjects are birds, this is problematic. With the Nikon lenses that have VR (Vibration Reduction) that levels the playing field on shake reduction. With Pentax every lens gets VR from the camera body. For Nikon the list of VR lenses is nice but not as expansive as the choices you get with Pentax.
I know we brag on the durability of Pentax gear, but I have to give props to Nikon for building a durable product. One of my Nikons has a shutter count over 182,000.
In summary, I will keep using bother cameral brands as they both have their strengths. My Pentax is easier to use and has in body shake reduction. The Nikon has a stronger auto-focus. I hope this helps anyone wanting a perspective on the two brands.