If the different in price isn't a deciding factor, I don't know why anyone would choose Pop! over CSR or any other moderate resort.
CSR has a great theme pool, several smaller pools, hot tub, fitness center, spa services, etc.
There is an in-room small refridgerator, coffee maker, and the toiletries are upgraded so you get separate shampoo and conditioner bottles. There are doors that separate the sink area from the main room rather than a curtain at the other mods (and values?).
There is a table service restaurant Maya Grill, Pepper Market which is a counter service breakfast & lunch buffet and has a regular menu for dinner, Cafe Rix which is a grab-and-go place with pastries, breakfast items, etc, Siestas by the main pool which serves a few food items, Laguna Bar, and Rix Lounge which is a nightclub place.