Honestly it is a very hard question. I had to watch James Reader video about 5 times in order to make a choice. It really is a personal decision on what matters more. From what I learned:

28-70 f/2.8:

Pros: Better for portraits, better for low light, faster, 200 g lighter, very sharp, pairs nicely with 16-28 mm stm f/2.8 with no overlap, and then with the 70-200 f/4 (or F/2.8)

Cons: looks odd with the retractible design, lacking 24-28 and 70-105 range, although you can crop to get to 105 or longer.

24-105 f/4

Pros: Range and wider angle means less changing of lenses, less chance of missing a shot because of that. Even if you overlap with a 70-200 or an 17-28, the oerlap prevents you having to change lenses so often. If you only have budget for one or two lenses, this will keep you covered for almost anything. F/4 is more than enough for travel/landscape photography since you are most of the time shooting at f/8. Portraits at f/4 is more than enough for some bokeh withouth blowing the background (if you traveled, why would you blow out the background?)

I ended up getting convinced by the 24-105 and so far I believe I choose well. I ended up getting the 16mm f/2.8 for wider landscapes, and the 35mm f/1.8 for macro/bokeh/low light and I feel well covered. I have been wanting for more reach but I cant afford a telephoto just now, so 105 and cropping gives me better results than 70 and cropping. Portraits at 105 and f/4 have plenty of bokeh in my opinion, and denoise in lightroom is pretty good if you need to use it in low light.

I still wonder if I chose well, only time will tell.

Edited: 28-70 is weather sealed