It makes a difference in what camera I use, but I’m not just referring to image quality. I used a long lens on my K-3 II to make the picture of the Spiderwort flower because I couldn’t get close to it. I used the small X-E2s with a prime lens to make the picture of the new leaves since I didn’t have room to use the bigger camera and lens and I wanted a fast aperture to blur the background. I had to use the X-E2s in a small space between the house and the leaves.
The size of the camera and lens also makes a difference when I’m carrying them among people. Most people get camera shy quickly when they see a large long lens pointed at them. In those cases, it helps to stay so far away that they don’t realize I’m taking their picture.
Which camera and lens I use also makes a difference in low light. I find that the bigger sensors do better in low light since they have less digital noise. Another factor is the loud noise of a shutter and mirror which are mechanical and moving and stopping quickly. With the smaller mirrorless cameras, I can use an electronic shutter which makes no noise.
I am also finding that it makes a difference in the age of the technology. Older sensors are not as good in low light. With newer sensors and better in-camera processing, the image quality is better in low light than for the older versions. Another factor appears to be the computer processing of images. The latest versions of Adobe Light Room seem to be better. The newer sensors also usually have more megapixels. This helps when I use a prime lens since it gives me more room to crop-zoom.
Another factor is the cost of the cameras and lenses. The DSLR lenses are larger but they are also less expensive than their mirrorless counterparts. A reason I purchased the Pentax K-3 II was to obtain the 55-300mm PLM WR lens which is weather resistant, and less expensive than mirrorless lenses that are available. I am finding that it is more suitable and cost effective as a field system for flowers and wildlife; but, not for photographing people up close.
My cameras are like “different horses for different courses.” The question is always, what will I want to use in the future? My Pentax is probably my last opportunity to use a weather resistant DSLR with an optical viewfinder to photograph wildlife, etc. outdoors. As I get older I am still looking for a personal walk-about system with prime lenses. Will that be a Fujifilm system or will I go back to a micro 4/3 system? I am currently also missing an articulated LCD. Will that be a necessity for my next system?