I'm in love with the Zeiss 15/2.8, but it comes at a steep price. I wanted the very best UWA lens for landscape and architecture, and its quality is undeniable.
That said, I've heard amazing things about the new 16-35/4. I'm sure it's fantastic, and far more versatile than the Zeiss 15.
yes, Zeiss 15mm is my dream UWA lens, but as said, the price is too high right now