At least I would give them them the award as the girlgroup that have made the most amazing climb from the bottom to the top. It took them 5-6 years from their debut to the double hits with Nonstop and Dun Dun Dance. Dun Dun Dance is one of the best kpop songs in my opinion.
I liked them allready with Liar Liar, but did not thought much of their songs after that before Nonstop. Their songs feels like pure kpop, even if not all of their songs are great.