I think they are both excellent fragrances. While based on the notes and everything I should prefer XXV, I actually prefer J25. Why? A couple of reasons:
J25 is a very complex scent. Perhaps the most complex scent I've ever encountered. The layers and orchestration of the composition boggles my mind and despite many wearings I still have not fully wrapped my head around the scent.
I find J25 to be more elegant and mysterious. On a man, I don't think it reads as overly feminine as there is a nice dose of incense, the herbal tarragon, the balsamic resins, and perhaps most importantly the animalic aspect. I think there is some castoreum present here as I get that dark inkiness that castoreum provides. There is also oakmoss present (as per the box), and this adds a bit of an animalic edge with its smoky, salty, 'human' qualities.
I find there to be more 'colors' present in J25. I experience a strong synethesia with the scent and experience vivid yellows, golds and purples, later the yellows become more ochre and orange as the amber becomes more ambergris like. The myrrh is a dark red and the anisic elements of the tarragon along with the winey grapey davana conjure up purples, along with the hints of black and green from the inky castoreum and vetiver/moss/patchouli in the base. I was trying to find a picture of an elegant middle eastern style dress that has all of the colors present that I experience in this scent - this is the best I could find.
Although the elegance of the scent makes me think of a dress more like this in style:
So, imagine the second dress and cape (er, what is that thing called?) with the colors of the first, and that is what I imagine J25 to smell like.
Now, don't get me wrong, I think XXV is a great scent, I just think that J25 is more unique, especially
for men. On a woman it smells womanly, but on a man J25 tends to smell.. well, maybe I shouldn't have used pictures of dresses up above to represent it because I don't think it smells feminine on my skin but instead just very very exotic. Like the male clothing equivalent - same colors and same level of elegance and almost ostentatious display of opulence - of the dresses above.