When I published my daily piece on the spoiler for From the Vault: Angels I touched on what I thought were the high value cards in the set. User "dean" pointed out that the new art for the Akroma's is a relevant factor. Many players simply prefer to use the original printing of a card, and when it comes to foil enthusiasts the preferred choice is almost always the original printing, as they'll be the most scarce. There is a different crowd- the Vorthoses of the world- that will increase demand for pieces with great art.
Art isn't an easy topic to debate- at least for me anyway. You can prove that certain techniques are more difficult to master, and there is a science to aesthetics, but at the end of the day what is going to matter is the popular opinion. I personally think the new RAkroma art is a huge improvement over the original in terms of aesthetic appeal, but that's just one guy's opinion.
To get a better gauge for popular opinion, I would appeal to the poll at originalmagicart.com. According to their numbers, the FTV Akroma, Angel of Wrath is the most popular of the three arts with 50% of the vote, with the new Akroma, Angel of Fury beating its old counterpart with a whopping 70% of the vote!
Currently the FTV RAkroma can be had for right around $10, with the original foils still sitting above $20. Over time I would expect the FTV version to approach the value of the original foil, though the more limited supply of the original will always be a factor.