Congrats on the new camera! Getting new gear is always fun

Personally I have the 16-35 F2.8 L III and really like it, but it is expensive. For landscapes you likely don't need the f2.8 so you can save some money (and weight) on the 16-35 f4 L IS which is very highly regarded (although I've never used it). For another more budget option the 17-40 f4 L IS was always (and definitely still is) a great option you may want to consider. I'd probably stay away from the older 16-35 f2.8 II as you'd probably be better off with either of the f4 lenses for landscapes.

Stephen