'I'm more of a Canon man myself,' I'm told on a regular basis when someone sees my cameras on a shoot. When pushed as to why, there's usually a mumbled response before said person wanders off on their merry way, leaving me none the wiser as to why one brand is better than the other.
I use Nikons. I've used Nikons for over 25 years, along with other brands, but most of my work is shot on Nikons. It happened to be the camera model I chose when I bought my first used SLR in 1997. What drove this decision to choose this brand? Price. It was what I could afford at the time, a used Nikon F401 with a 35-80mm lens. Over time I purchased a couple more lenses, and was then invested in the Nikon system. More Nikon bodies meant a deeper investment, and so on, until a decision to now change manufacturers would mean a hefty investment in new equipment, while trying to claw back what I've already invested in my gear. What would I gain by doing this? I have no idea. I do look at new camera equipment coming out, and think, 'Wow, more megapixels. Better focusing, better image stabilisation.' Will it improve my photography? Make me a better photographer? No. I'd be better off improving my technique, focusing on what is lacking and working on that. Make no mistake, there are some cameras out there where I find myself revisiting the manufacturer websites to see if for some reason a zero has magically fallen off the end of the price, making it feasible for me to purchase their basic models without remortgaging or winning the lottery, (Phase One or Hasselblad, if you're listening...)
I use two main cameras these days, a Nikon D4 and a Nikon D750, although lately I've been favouring the D750, as it's the lighter of the two bodies and the flip-out screen helps when composing very low shots. The youngest of these two is now 8 years old, both have shot hundreds of thousands of images between them. The D750 has had a new shutter system in it, as I wore out the original one, but they do what I need them to do. Overlooking stupidity on my part, leaving batteries or memory cards at home, they have never not worked when needed. They are both full frame sensors (the digital sensor being the size of an original 35mm negative), giving me plenty of scope when printing larger images. The D750 has the edge in low light, making it ideal for astro photography. The D4 is super fast, making it great for any action based photography, not that I do much of that these days, but between the two, they cover my needs.
If one of those zeros were to magically disappear though, that would be a different matter.