Alan, thank you very much for taking time!
I have to confess that I am not overly obsessed with gear even though I enjoy using good quality cameras and lenses. If you will check my photographs then you will see I am 50% landscapes and 50% portraits. I tried many different lenses for portraits (35 mm, 50 mm, 85L and 70-200 II) and today I know that 70-200 II is my go to portraits lens. It covers 85L for me. So far I do not feel any gap when it comes to portrait set up, I am fulfilled.
When it comes to Landscapes, 24-105 was my only lens for many years and I simply invested money in travelling - I went to Tuscany, Iceland, Chamonix Mont-Blanc, Costa Rica. I decided to spend money on traveling rather then on new lenses. I am mostly into practical usage...I have never done any pixel peeping. I know that 24-105 has limitations and I wanted to check if landscape photographers that travel a lot....spend time in the field....do they see a day and night difference.
There are things that I care about....I checked that 24-70 II is 20% heavier and I think it also has the extendable zoom ring....this one thing that I dislike about 24-105.
I could go to 24-70 II and it would have been for landscapes only. I do not need F/2.8. If at F/8 - F/14 there is not going to be a significant difference, I would not even bother. Yes, I do have 16-35 F/4...I purchased it a couple of weeks ago. It is a nice lens, I am happy I got it.
I went to the-digital-picture.com and read the review of 24-70 II. Bryan says that when it comes to landscape photographers, it is not a very easy task to say which way to go (24-104 or 24-700 II)....so there can't be such a big difference, I think.
As for the high MP and better DR camera body- I personally think it will make a difference. Looking at Nikon D810 files....there difference is there.
AlanU wrote in post #17251459
Pilgrim, I realize your looking for a lens for landscape application but I'd be looking more for universal use.
Do you own a 16-35L f/4IS?? or mk1 f/2.8? mk2 f/2.8?? If you own the newest 16-35mm f/4 version I think your set for an extremely capable landscape lens.
If you looking into top notch image quality across the entire FL of a zoom the 24-70Lmk2 is undeniably a zoom that gives you prime lens quality. The 24-105 cant touch that at all.
If there is no discussion about budget and simply choosing a lens for pure high quality images there is no doubt the 24-70Lmk2 trumps the red L ring "kit lens".
As far as funding for a 5dmk4????? Your better off buying the superior 24-70Lmk2 for a large jump in image quality VS buying a new full frame camera that WILL NOT make noticeable IQ differences for typical prints. Even if Canon slaps together a higher mpx camera to 36 or 45 megapixels the image quality will not surpass a 5dmk2 or 5dmk3 for portrait work....unless your shooting for billboards or huge posters.
If landscape isn't your true passion you can use any decent lens on the market. If your putting great efforts in shooting the best landscape photos possible even a sony A7R would surpass most Canon dlsr's due to higher megapixel count. Yes off topic but the point is using the eyepiece to the world (24-105L) isn't the best set of eyes

rent/borrow a 24-70Lmk2 and you'll be able to use that for portraiture and landscape. If the reach isn't long enough and you want at least a 100mm and light form factor the 100L macro lens produces similar lush 3d imagery and micro contrast like many new generation Canon lenses. Slightly off topic but something to think about.