I have to say Blastoderm for a multitude of reasons. Players have been clamoring for reprinting Juzam Djinn for as long as I've played the game. What are the strengths for Juzam Djinn?
A) Black removal can't destroy Juzam Djinn (in general). Blastoderm does this!
B) Juzam Djinn is a 5/5 for 4 mana. Blastoderm does this.
C) Juzam Djinn's drawback is meant for fast beatdown. So it's Blastoderm's obviously.
Now, what does Blastoderm have that Juzam Djinn doesn't? First of all, Blastoderm was printed in a small set in large quantities as a common. This results in a LOT of Blastoderms out there. I've got at least 14 of my own just sitting there. Second, Blastoderm is green, the color of now the best creatures in Magic, and considered by many to be the casual player's color. All of this leads up to why I feel Blastoderm is the best Fading card: Wizards proved that it listens to it's main customer, the casual player, when they printed this card. It could have easily been a rare and as hard to get as Phyrexian Scuta, which is considered to be the premiere replacement for Juzam Djinn.