Light elementals are clones of fireflies from the human dwelling, so it's just embarrassing.
Dark elementals seemed interesting to me personally, and their abilities are decent. I voted for them.
Fire elementals don't quite match their element; they're a kind of mix of fire and earth, and in the third game, they were called magma elementals. I also didn't like them because they look silly.
Water elementals are clones of river nymphs from the city of Nag, so they're also embarrassing.
Earth elementals are so-so. But they're not too original, except that the presence of vegetation is pleasing.
Air elementals are some kind of monstrosities; they definitely aren't contenders for a prize. :)
Mermaids didn't impress me, to be honest. They need to decide whether they're fish or dolphins. If they're fish, then they're clearly aquarium fish; their tail gives them away.
Phoenixes are good, and the idea is original. I initially wanted to vote for them, but I decided that the developers went a little overboard with the proportions.
That's how it is.