Indeed, the uncoated Sonnar is great for B&W. With a proper hood and You wont need coatings, flare or haloing is going to be nonexistent except when shooting straight towards the Sun - but who really shoot like that and how many lenses, even coated ones can hold it up with such light?!...
Zeiss Ikon Contax II is probably the best in the 35mm department, a lot improvements since Contax I, also its build way more solid, technologically, than even Leica.
It might not be as elegant on the outside but its a beast under the hood.