Arctic Photo said:
Well, it's another one of those impossible questions. But as it involves my favourite lens I will reply. Just get it, there's no way you will be disappointed. It's a 16 year old construction but still performs amazingly well for me on my 5DIII. When the Mk2 comes out you won't have lost much anyway. It has a quality to it, something charts won't show, you'll notice the first time you put it on, feel the balance, snap your first shot and look at it. I love mine and will never sell it. My next purchase is the 50L, no matter how good the Sigma is. I understand the 50L has a similar feel to it as the 35L. But that's only me, that's what photography is to me - feel.
The 50 Art has much more of the same feel of the 35 L than the 50 L, because the 35 and 50 Art has way better sharpness and the shots pop more. You can use corners wide open, not so much with the 50 L.
Beyond that, I have owned six or seven 35 L's and I have shot at least 100k images with them, but IQ wise, the 50 Art destroys it. Much sharper all over, veryvery little ca, no distortion, color and contrast are much better than the 35 L. I know what the feel of a lens is, and I absolutely agree that the 35 L has the x-factor, but for a 50, I would never buy another 50 L when the sigma is out and that much cheaper.
Why I want the 35 L II is because it will be weather sealed, it will be sharper in the corners, less distortion, and color and contrast like the 24-70 mk2 or better and it will absolutely 100% sure be the best AF performance of any 1.4 lens.
Here's a recent 50 art 1.4 shot of my daughter. How sharp is that at 1.4 and how lovely bokeh? LOVE this lens!