All three cameras are interesting indeed. The A7R II could cause problems for both Canon and Nikon in that it supports PDAF for third party lenses... i.e. it should be able to Autofocus Canon Lenses well using an adapter with electronic contacts. That means people that have lots of Canon lenses could potentially change to Sony mirrorless and still use most of their gear and have stabilized prime lenses...something not possible using a Canon body!!! If I didn't already have the A7S, I would consider the A7R II for video work. I think the two smaller ones will be pretty popular however. They are moderately priced and are versatile. The RX10 II is basically an all-in-one event camera and the RX100 IV is perfect for vacations or just carrying everywhere.