Hunter is the best deck.
It‘s not a secret and it’s not surprising. Hunter is the perfect conflux of all of the elements that are powerful right now – deathrattles, secrets, and inevitability.
Deathrattles are powerful because of Undertaker
Mad Scientist leads right into the next point: secrets. Freezing Trap
Time is an important resource in today’s Hearthstone. Zoo is trying to set up an unbeatable board before you can establish yourself. Priest and Warrior control are trying to stretch the game out until they have time to leverage their superior late-game plans. Hunter sidesteps all of this by just killing the other guy. Steady Shot trades blow-for-blow with Armor Up! and Lesser Heal, and the other cards in your deck can usually deal the last few points of damage.