I hope the OP has gained from this thread. I know I have.
I too have a 5D, and count the 17-40, 50 1.4 and 85 1.8 among my lenses.
For my purposes the 50 is my most used walk-around lens. I like the composition I get with it, and enjoy the way it makes me think about the image I want. It also works very quickly with autofocus, which is often important with candids. I sometimes use it for portrait work.
The 85 is mostly used for portrait work. It suits my style and ability very well. With or without grip it is comfortable hand held.
If I had just the 17-40 and used it mainly for landscapes, I feel I would grab the 85 first. The 17-40 can be a great general purpose lens. The 85 would give reach and thus flexibility and is small enough to carry easily with the 5D and 17-40.