Which 70-200mm for landscapes?

I think if you aren't concerned about IS at all, and plan to use a tripod, I would seriously consider the 200mm 2.8 ii. It's only a little more expensive than the 70-200 f4. And gives you a little better options with a TC if you want it with it being 1 stop faster.

Since you have the 24-105, the gap isn't as bad as if you had a 24-70. Yes missing 105-199mm might feel like a lot, but in landscape work I'm not sure you require a zoom, since you have a little more flexibility in composition and timing.

If you feel like you have any need whatsoever for shots not on a tripod I would get the 70-200 f4 IS in a heartbeat, but if you really aren't worried I'd take a shot at the prime.