The best decks of the new expansion are old decks with a few new cards.
Hearthstone Fractured in Alterac Valley
Links:
Libram Paladin:
https://hsreplay.net/decks/kXaU1gy8t2DSIZ3lXzZbYd/
Buff Paladin:
https://hsreplay.net/decks/HdLv9bpDfiaLi1NqX0kUM/
Aggro Elemental Shaman with Freeze Cards:
https://hsreplay.net/decks/qVztKPS9dmDZbpsChJo6r/
Garrote Rogue:
https://hsreplay.net/decks/Km2WaXL5YzaAXVnU6knX3c/