Hearthpwn

Rogue has a few flaws -- counterspell or a lucky Dirty Rat can throw the whole thing off. And if the shuffle isn't in your favor ... 

Priest is overkill in wild play with all the really good deathrattles, Reno Jackson, etc.

Mage has potential but most quest mages are f--ked if they can't annihilate your minions with doomsayer combos or Flamestrike. It's like watching neutered freeze mages drag the game to their own bad demise. Have been beating up mages using an elemental deck with my mage.

I would say Kalimos is a better card than the quest for shaman, unless you like chucking murlocs everywhere.

Toss-up between Paladin and Warlock for worst quest. I should know. I landed both of them. The lock quest is different and fun, but it ain't for serious playing. I've been getting my Lorewalker Cho some highlights, though; he's an underrated natural fit for discolock.

Paladin quest, however ... I've had more success with the elementals in a deck I'm trying rather than the summoned Galvadon. When everyone knows you have to buff minions for a potential OTK, they usually do a good job cleaning your side of the table, or tuning up the aggro. Or saving a super board clear or major debuff for when Galvadon gets dropped.