I would say to let your daughter choose which one she likes best. Probably by looking at the pool area on Disney's webpage. I'd also check availability.
It's kind of a toss up as to the best one:
POR is my least favorite. POFQ is compact, but my least favorite food court. POFQ has a very cute, but tame water slide. She might be brave enough for it. Probably the best pool for her, but read below.
CSR, CBR, POR are quite large. Least bothersome at CSR because sometimes staff will let you ride on golf carts (or at least they used to do so).
CBR's main pool is being renovated. It is due to open SEpt 15. Before then it willbe closed, but after it opens it looks like it's goign to be REALLY COOL!
CSR has a really great pool! But she proabably is too little for water slide.
All four mods have water (lake or river), so a good chance to see wildlife: ducks, birds, bunnies, etc.
POR and POFQ have a free boat to DTD. If you are going there, it is nice. Otherwise you can just take the boat between the two resorts for fun. CSR and CBR have boats you can rent.
I disliked buses at POR most, second worst was CBR. CSR buses make multiple stops, but are often not crowded. You will see convention folks at CSR (So they may be drinking at times). POFQ buses are sometimes direct, and sometimes they also loop POR.
As far as daily activities,I think that's mostly at the Deluxes. Sometimes the mods will have pool activites. CSR, CBR both have playgrounds. POR and POFQ have horse carriages at night but they are $$.
