Both are beautiful! I have both of those bags. Green is my favourite colour, so I do like the Olive - it is why I ordered it! The Prussian Blue I ordered on a whim, before it disappeared from the site again. I had no idea how I would feel about it; it is my first blue bag as I never was drawn to most blue bags.
Honestly, as much as I love the Olive - it is a great and versatile neutral that works well with my wardrobe - if I *had* to pick between the two for only one to keep, I would go for the Prussian Blue, hands down. The colour is rich (much prettier in person), yet versatile, the black contrasting suede & handles look perfect against it, and the whipstitching/rip & repair are beautiful added details that also add a personality twist. I think there are no issues with it crossing easily back and forth between work and casual.
So tough choice, but the Prussian Blue is actually my favourite of my three medium Rogues - I also have Butterscotch - and it was the one I expected to like the least!