Trying to switch to mirrorless and tried many different brands (used). The best ones, in my experience, are Sony and Fuji... I got a used Sony A6000 for $200 used body only recently a used Fuji X-T100 for $325 used body only.
I used the "kit" telephoto lens on both (E 55-210 and Fuji X 50-230). Both have 24mp APS-C sensors.
I took both out for Aviation photos by the Airport Yesterday.
The Fuji does have better out-of-camera picture quality, but the Sony "totally smoked" the Fuji when it came to action photos focusing and exposure. The PQ was pretty close.
I found the Sony EVF to be better and the camera easier to hold...
Seems like Sony has done its homework when it comes to features and usability...
Sony is smart if these "V" lenses will work existing APS-C bodies, those are my next lenses. I'll eventually end up with a Sony Compact Full-Frame Camera, if not, I'll stick with the Sony A6000 series.
I tried a couple of MFT mirrorless (Panasonic and Olympus) - the sensor didn't really hold up to me shooting in low light and cropping...
Gonna keep my Olympus OM-D EM-5 for old time's sake (Olympus was my first dSLR back in the day).