Here are my ratings for each Element's nymph.
Aether - Not very good. Because of it's weak ability, it's only useful to provide damage in a rush, but Aether doesn't really have any Rush cards.
Air - Not very good. It's too slow against a rush, too expensive against a denial, and too frail against a stall.
Darkness - Not very good. Its ability isn't something you'll need more than once or twice.
Death - Not very good. Aflatoxin is better, but not even Aflatoxin is any good.
Earth - Not very good. Too slow against a rush and not helpful against a stall or denial deck.
Entropy - Not very good. It's way too frail and can only be good against something with no CC, but it's too slow against something with no CC.
Fire - Not very good. Due to its ability and stats, it could only be useful against a rush, but it's too expensive in an anti-rush deck.
Gravity - Not very good. Its ability is only decent against rainbows, but rainbows have CC to easily kill it.
Life - Not very good. Adrenaline is for rushes, but this is far too expensive for a rush.
Light - Not very good. Slower than Luciferin, hardly does any damage, and its healing isn't as powerful as Miracle.
Time - Not very good. There's no need to want Precognition more than once. Hourglass is better for draw power and GotP is a better attacker.
Water - Not very good. It's an unreliable and expensive way to summon something that isn't even useful.
Conclusion: Stop complaining if you don't have any nymphs. They all suck.