I have had a Canon 6D and a few nice lenses (24-105,85 f1.8, 70-300L) and about 6 months ago I picked up the Sony A7II in the hopes I would eventually sell all the Canon gear and stay with Sony. But that hasn't happened yet and I can't seem to understand why. The Sony is smaller, lighter and in some respects better pictures. I started off with the usual cheap manual focus legacy lenses and have had fun playing with them. I then purchased a used FE 24-70 and recently traded it for a FE 55mm and find the 55 much sharper. Yesterday I played with the Batis 25mm f2 and was shocked that it was so light, and the focus was smooth as butter, but at $100 per once it is way too much compared to Canon and Nikon high end lenses. This only makes it harder to switch totally. I bring all this up because I have a 65th birthday coming up and my wife wants to get me something special and a new lens was one of the things I am thinking about and also a 4K tv but I think I will wait a year or two for that. So now if I go with a lens I don't know if it should be for a Canon or something for the A7II. The Sigma 24mm f1.4 Art has caught my attention as well as the Canon 24-70mm II or the 100-400 II. I would like to get the Sony/Zeiss 135 A mount but then that requires the adapter which only adds to the size and weight. Also I do prefer auto focus. Any other suggestions?

