For landscape photography I'd prefer using a zoom. I don't believe either 14mm takes filters all that easily. If you're shooting f/8 - f/11 then the 17-40 is likely good enough unless you need f/2.8.

There's a huge difference between 17mm and 40mm and having the choice of focal length quickly available to you is greatly valuable.

As a bonus the 17-40 is fantastic against flare.

Dave