Image on top shows the current 55mm Otus.
The best lens of th world you can use on any mirrorless camera with an adapter is the Zeiss Otus 55mm f/1.4. Well, if you have the money and want the best than you will be also happy to learn that Zeiss will launch a new Otus 85mm f/1.4 lens in 2014!
Price should be again around $4000. Start saving the money!
Here is the official message from Zeiss:
Note: The Otus 55mm is the best lens ever made according to DxO testings (Click here).