Do you like 40mm on the 17-40? I find it stays on my 6D far more than my 50mm. Those 10mm make a big difference.
I've shot with the 24-70/4 IS, and the 24-70/2.8 VC in the last month. I found I really liked the 24-70VC, but I also love the 35mm f/1.4. It'll depend on what you shoot the most.
I'd sort your LightRoom or your Aperture by list and focal length. That will likely really help with your decision.
Hi, I find I don't really use the 17-40 using the full 40mm but I do use it a lot around the 30mm and 35mm range. I would like to have both at some point I'm just trying to find which one to have first. I'd like it more for portraits at the moment. If you've used both, how does the tammy 24-70 2.8 vc bokeh compare to the sigma 35mm 1.4 bokeh? Thanks for the info
I'd reach for the f/1.4 every time if I were shooting portraits at 35mm. At 35mm, 2.8 really isn't enough to throw the background sufficiently OOF in my opinion. The Sigma 35mm bokeh can be harsher than the Canon L bokeh in my opinion as well. If I were buying a 35mm solely on bokeh quality, I'd buy a used Canon 35mm. If you're taking landscapes or other things you want extremely sharp, you may want to go Sigma.
If you are looking for a "traditional" portrait where you focus on the individual, and have no regard for the background being in focus, or really showing where the person is, I'd go with a 70-200 f/4 even, or a 100mm or 135mm as the length really helps with narrowing depth of field. At 125-200mm and a close subject, even f/4 is enough to really throw out the background.
If you want to shoot "environmental" portraits, where the surroundings of your subject are important, one of the areas I really struggled when developing as a photographer was using too wide of an aperture. I.e. I have portraits that I intended to be environmental, but the environment is entirely out of focus. The worst was when I tried to compromise and have a half blurred environment. Since then I've started using my tele's for portraits, and a 35mm or similar, usually my 40STM for environmental portraits, and not worry about keeping a small DOF.