Ended up with my vote.
When I play Darkness FEELS like darkness and when I go against decks with Darkness, I FEEL it's shadow.
It has a couple good synergies even when the cards don't lean towards it, it's cards are still useful.
Obvious Synergies
But
or
not as obvious, but pests, with mitosis or fractal pests, once setup can be hard to stop
or
perm denial to the extreme...
It can stall two ways both mana delay, and creature delay/denial.
It can heal multiple ways.
It can do serious damage multiple ways.
Has lots of little tricks up it's sleeves
It can protect itself
It has STEAL, both Perm denial and the ability to use them against them, only Aether has and a lucky Pandemonium can pull that off.
Gravity feels like GRAVITY, as in something heavy is pulling on you. Titans, Dragons, Overdrive and BlackHoles feel oppressive, like, how the F do I block that, oh yeah I can't... Where are those reverse times, where is that damn elf, F me... Yeah I got one, oh but he just took all my mana, son of a ... It's not creative, it's not the most synergistic, it's not much of anything other than hard hitting like the ground after you fell from an airplane.
Then Entropy, it feels like Entropy, it runs like entropy. It slows you down, goes to the edge of physics and starts warping things, unlike Darkness or Gravity that I fear getting smacked with a mono Entropy feel's easy... Entropy by itself simply runs out of steam, which is basically entropy at work. Entropy with anything else is pure chaos smack down...
It's what fuels the speedbow, it has a home in any rainbow, it can rush, deny, or creature control with the other elements... It's the perfect partner with another element. Oh and it's got antimatter... DAMN I LOVE/HATE that card sometimes...
A solid honorable mention is
and
Both have some unique great abilities
I personally love time, but I feel as if it doesn't completely play right, Eternity is it's heart, but it's creatures are off, Pharaoh, Ghost of the Past, Time Egg, Deja Vu, none of these FEEL like it's element quite right... Deja Vu, kind of, but past that, sorry. I feel these cards should effect time, like cause delays in other cards, or have multiple attacks, or come out with a three turn delay and wait out to become a bad ass.
Same with Aether, I feel it's also lacking proper feel, It's like they took a bit of each of it's various meanings through time and slammed it together, Aether feels like something solid and firm, it should feel as if it's raw, immaterial, and abstract... Take the feel of water for example, and apply it to the extreme, where Time messes with Time, Aether should mess with matter. Cards that cause creatures to fade out and in, pass through shield or make weapons immaterial, creatures should pop into play almost randomly or be made of out pure energy.
Other elements suffer from similiar feelings, fire should be hot to play with so to speak, it's got it's burn but only so far, fire burns as long as it's fuel source is still there and is hard to control... It's got the heavy fast damage feel but that's about it.
Death, similiar, death should have 4 heads so to speak, and it only shows two...
Life, life is dynamic, life here to static, life is not all about little creatures although mitosis started getting it in the right direction.
Light, light has pretty good representation, but it doesn't counter darkness as well as it should, granted it has a couple cards targeted against it, but it almost feels like Life, but in a different form, Life and Light are not the same... but here it plays similiarly.
Earth feels like earth, but it's incomplete, and it's synergies feel out of place... Earth and Water for example should have very powerful synergies, there are none... instead you find it's synergies outside it's tradition family of elements, earth and gravity, earth and time... it feels as if it's not at home. Air and Water probably have the tightest realization, such as freeze/shockwave combo...
So that's why I chose what I did... sorry it's wordy.