Such a difficult choice, because they are both fab!
I have some white soled boots (in Finds), which after wearing, I wipe down with a sponge if they look marked. This is my second year of wearing them, and they still look clean from a distance, but up closer, they are showing a few light marks despite my best efforts.
I have lots of boots I never wear white boots when I know the ground will be dirty - this is fine because I have others that can be worn in those conditions.
My vote is go with the ones that you like the most. Yes, the dark soled boots are more practical BUT you have lots of practical boots already, so it will not be too difficult to look after the all white ones if you prefer them.