There are a couple of reasons for this...
You want creature control?
We've got that.Permanent control?
We've got that too.How about damage?
Loads of it.Quanta denial?
You bet.Draw denial?
Oh yeah.Healing?
More direct healing cards than Life has... and as many as Light.*Stall-breaking?
Just try to stop us. "And now, the Darkness holds dominion... black as death." - Darkest Dungeon
* Darkness: Vampire Stiletto, Drain Life, Minor Vampire, Liquid Shadow, Nightmare, Black Nymph (6)
Life: Heal, Druidic Staff, Empathic Bond, Shard of Gratitude (4)
Light: Holy Light, Miracle, Luciferin, Sanctuary, Shard of Divinity, Light Nymph (6)
Well, I'm not actually a kleptomaniac... but I do share a pretty strong emotional connection with the Dark.
I love the night. Just about every single one of my fondest memories since my childhood has happened with the sun down - in fact, having to go to sleep before midnight actually has a pretty negative effect on my mood! I often go for walks alone in the very early hours of the morning - not something I share with many people, but I suppose it's fitting here. Rather fittingly, black has always been
my favourite colour.---
Competitively, Darkness is, without a doubt, my favourite Element to play with. A couple of you have already mentioned "versatility" in this topic...
The versatility you find in light is like no other, except with fire. But their versatility is like yin and yang of eachother.
Light, because I feel like Light represents me. Versatile, easy to work with, durable.
If I'm completely honest with you, I think both of these statements are rubbish! There are only three Elements in this game I think the term can accurately be used with - Fire, Aether, and of course, my beloved Darkness. The power to either completely obliterate your opponent's health pool, or decimate their entire offensive force simply by changing a few in-element cards - that's real versatility.
I'm really proud to hold the title as current Master of Darkness - winning a master title was the #1 Elements goal of mine from the day I came to this community, and I'm very pleased to hold it for my favourite element. Leading Darkness to its first War victory, with the highest winrate in history, was a huge personal achievement - getting both the Most Exquisite and Most Successful deck awards was awesome, too! With the 2nd Grandmaster Battle underway, I hope I can make my element proud by putting up a good fight against RootRanger.