So, I'm taking the plunge and buying an FX body, the D850. Although I mostly prefer using primes, I'll also want a general purpose walk around zoom, but am getting conflicting advice from D810 and other FX owners I know.
I don't have good endurance and hills knock the wind out of me, so nothing too heavy for an old fart like me. If I need big gear, I bring the car, lol.
I didn't see any noticeable differences in IQ between 24-85VR/24-120f4/Sig24-105, except the extra reach by two of them. For walk around and travel anyone of them should be fantastic, with 24-85 being the best in terms of weight, size and price.
If you are very very particular about landscapes, or portraits or macros then you need to forget about the word 'walkaround' as they are all seperate genre, you may need to go for specific lenses that too different lenses like 20mm 1.8 or 1.4 for best landscapes, 85mm or longer telephoto prime lens with f1.4 for best of the best portraits and other specialized lens for Macros(and i see that you already have a couple of macro lenses).
So, bottom line is, since you are looking for a 'walkaround' then 24-85VR without expecting super landscapes/portraits/macros. But it can do everything with acceptable IQ or even better then acceptable pictures if shoot RAW and process it to your taste and liking.