I don´t know the Zeiss, other than all the positive things written about it.
I personally love 24 mm. I think that is the best wide angle you can get, before your side perspective gets too distorted. I have had the 17-40 and both versions of the 16-35 (still have 16-35 vII) I hardly used or use them.
The 24 TS-E f3.5L II is a great lens. Without using the tilt & shift it still outperforms any 24mm I have seen, except for the fact that it is manual focus. With the tilt & shift you can do awesome things with it. A lot of people think architecture when they hear of T&S lenses. But they have lots of great use in nature and landscape photography. you can create incredible depth of field and correct perspective in forests etc. You can also create very cool effects, by shifting the focusing layer vertically, to be an angle off the straight parallel line you get with all other lenses.
If you are willing to spend the time it takes to exploit the potential of this lens, you will see many great results. You need a good camera body, a good tripod and lots of extra work pr. shot. But in my view, that is what makes photography fun.