I'll run through the rest of the contenders here and talk about their pros and cons, but really it might all come down to the metagame you predict and the way you like to play the deck
Since many rats care about the number of rats you have, cards like Pack Rat, Ogre Chitterlord and Vren, the Relentless are enablers and payoffs for the strategy, creating rats that grow in sequence with one another
This is more of a casual, themed deck, but with the right metagame and new supporting cards, it could be a competitor
This unique composition creates a formidable barrier against tears and wear, ensuring that your cards remain intact and unscathed, even in the most demanding of situations
Cards that are too expensive (7 or above), too hard to cast, or just don't make an impact on the board will generally go in one pile per color