I own both. If you have to choose one, then choose the Prophets -- unless you're on the ice a lot. In that case, get neither.
For a ski of its width, the Prophet handles the front-side hard snow and ice conditions well; I found it to be fairly stable at speed if it's on edge. Where you want it is in the powder and off-piste, the conditions where it will dominate the Fury. The Fury will hold an edge better in firmer snow, but is not so hot in crud. I also find the Fury to feel a bit more nimble in and around trees.
The Prophet wants to be carved, will tolerate the slarve, but will not be smeared, while the Fury tends to be more forgiving with more turn shapes and styles. The Prophet demands respect from the user, but the payoff is far greater (faaaar greater). The Fury is more laid-back, and truly is, as I believe SJ said in another thread, a Jack-of-all-Trades but a Master of none.
And to throw a wrench in here, I also had a festive day on the Mantras. I went with the Lines because I had more control over them flying through sketchy on-piste conditions.
EDIT: There is a discussion in the Ski Gear forum (where it bejongs) about the Prophet 90s. They will handle the front-side conditions better than the 100s, I'd think.