I just recently became a fan of Craniax the Quick.

Until a few days ago I rarely thought about that card, but then I saw it in a battle with the Born again ruleset. Craniax pretty much single handedly destroyed the enemy line up with it's Final Rest ability.

It might not be the best card in most battles, but in some cases it can render a whole line up completely useless.
That's why I currently consider it my favorite legendary card.