|A7 with 70-200mm f/4 on the left, and the Panasonic GX7 with 70-200mm (equiv) f/2.8 on the right|
In peeking at other systems, it's become clear to me that if my photography was different, I might be using other gear. So, what do I mean by "different?" Let me explain by using longer lenses as an example.
I'm not a regular "long" shooter. I have, and like, the 70-200mm f/4. But I bought it for portrait work. I wouldn't want to carry it around all the time.
Have a look at the photo above (generated using camerasize.com). If telephoto was an arrow in my daily quiver (or if I planned on traveling with it), the Panasonic on the right would be looking pretty good to me. And, it should be kept in mind that the Sony on the left is small compared to the full-frame, f/2.8 models.
Don't take this as a recommendation for that Panasonic lens, however. If anything, it's an admission that I'm probably not the guy to ask if you want to focus on wildlife, or landscape, or sports, or macro.... You get the idea.
|A7 with the 35mm on the left, and the Fujifilm X100T on the right|
Picking Sony was relatively easy for me, because I usually stick to the tried-and-true trio (a moderate wide-angle, a "normal," and a short-telephoto). I find that Sony's 24 megapixel sensors work for me because I print regularly at A3 and above. But, if I did landscape regularly I'd probably gravitate to 36mp.
Horses for courses.