Wowowow!
Just started laddering with Zoolock, insane deck. Very very high win rate against shaman which is the class I see most often. Usually is an auto-concede against Priest/Patron Warrior. Very good match-up against Rogue (only lose if he has an insane start with multiple backstabs n such and I have a bad start). Probably 45-55 against Druid, depends on what type. And I'm 65-35 against aggro paladin, and 35-65 against N'zoth stalladin.
I think the most important thing about using Zoo for laddering is the game length. I know whether or not I've won by turn 5 90% of the time, meaning I'll just drop a concede quickly and move forward to the next game, or just finish them in the upcoming turns. I've even conceded as early as turn 3 because I understood the situation. This makes for an extremely low average game length, perfect for the monotony of ladder climbing. My favorite class is Warrior, and I'll often pilot those decks for 9 minutes a game, which if either way I rock around 55% win percent, I'd much prefer playing 40 games a day to 12 for laddering.
1 star away from Rank 7. I MAY go for legendary this season, don't know.