Okay, here's my opinion:

a: Nothing wrong with the original, I like it a lot.
b: I like it a lot too, only the center (post area) should be darker.
c: The buttons are unreadable on my screen, otherwise, it's nice.
d: I really like this one, I can't say anything bad about it.
e: There's something about the colors that gives me a bad impression about this one.
f: The main colors are good, but the buttons are horrible. I want to scream when I see the contrast between the blue and the yellow.
g: This one is really nice, but the center needs to be a lot darker, if not even black.
h: Reminds me of the original synthesis in a good way. I can't say anything bad about this one either.

"Stephen Wolfram is the creator of Mathematica and is widely regarded as the most important innovator in scientific and technical computing today." - Stephen Wolfram