Reckon all these samples are hard to work with because the pic of the pools are all different angles, light, elevation etc. I am also in the same boat as you.
Don't think staining will be an issue, but based on my last pool I'm thinking the Arctic while will show more dirt on the tanning shelf than the French grey. In saying that if you vacuum regularly and the pool is inviting, dirt or staining should have no place really.
I see you have grey coping tiles, some grey fleck in the spa tiles, browny-grey earth tones on the house. For my money I think the French Grey would be my pick. I think that would flow nicely. Just have a reservation the Arctic may be to light or bright and not look as homely.
Nice pool, its going to be great.