Well the Fuji system seems to be a fairly good compromise. However if size is the primary concern, something like the RX1 or the mkii version is hard to beat considering the IQ it put's out, same with the x100 series as well. But then you lose lens flexibility. I love the fixed lens X100T, but I think it's the kind of camera you want along side an interchangeable lens camera system, rather than being your only camera. Sure with the x100 you have the wide angle and tele lens adaptors, but then you might as well get something like an X-T1 or XT10. And then there is the RX100 series. Great camera again and you can actually fit it in your pocket, but small sensor so you trade off image quality. But then you have zoom.. so...
Where would the Sony A7 fit in to that lineup. Just curious.