This is a hard one for me to decide on, we're not really comparing apples to apples here. (One being a moderate and the other a deluxe) I have stayed at both and love both of the resorts but they are so different in their own unique ways and have their own set of pros an cons.
CSR is a moderate so the price will be less expensive than BW. It is a much quieter location, being pretty much in the middle of nothing..(Which is one of the reasons I like it so much) The theming is beautiful and the rooms are cozy. There is an awesome pool and the grounds of the resort are awesome. I would say the dining is good, not great. While the grounds are beautiful, the resort is huge. Unless you have a car with you and can park at your building. It is a long walk to the main building if you are in any of the Ranchos buildings. I'm speaking for myself, but I never had any luck with the buses at this resort, found myself waiting for what seemed like eternity. (Yes, I know this can be an issue at any resort)
BW is a deluxe and therefore more expensive. But it is in walking distance to both Epcot and DHS and the Yacht and Beach Club (Which is awesome and beats the buses any day) The Boardwalk is definitely a more upbeat resort with much more foot traffic and things to do. It is gorgeous in my opinion and just feels like home. Dining on the BW is great! The Flying Fish is one of my favorite restaurants on property, and since they reopened, I like it even more. The Boardwalk itself comes alive at night with live entertainment and looks beautiful when all lit up. The nose coming from the Boardwalk can be bothersome if you have a room with a Boardwalk view and are an early to bed type person. I guess I don't have many negative things to say about the BW.
For me it really depends on what type of trip you are taking. I'll stay at CSR if its a budget trip and if its a family vacation, definitely the BW.
CSR I give an 8 because of transportation and just OK dining. The BW a 9 for proximity, dining, atmosphere and overall layout of the resort.
I would definitely stay that the Boardwalk!