Sony Zeiss FE 35 1.4 vs Sigma 35 1.4 ART. Worth the extra cost?

[Jlister]

I have Nikon system and Sony A7/S/R and I wanted to know if any of you have used both the sigma art 35 and the new Zeiss 35 1.4. I'm trying to decide which one to purchase. If the iq is that much better I will pay for the Zeiss but it is almost double.