I have a Sony a7ii and I love it! It's mirrorless & full sensor which is great but it took some getting used to for me not to hear the clicking of the photo being taken after all these years using a mirrored Cannon DSLR. What sold me in the a7ii was the full sensor, excellent low light capability & phase detect auto focus. I also like its versatility with lenses
I have no idea what's different between the a7ii & a7iii so I can't speak to the newer model.