Tough call! We did a split stay at RS (magnolia Bend) and FQ (Building 5) last year and we tried CS (Cabanas, with upgraded access to Business Club) this year. We spent about 4 nights at each resort, each stay around the beginning of May. You honestly can't go wrong with any of them.
CS was the quietest of the 3, but there were 2 conventions during our stay so we did have a LOT of drunk business people and cheer coaches hanging around Laguna and the beach. There was one small drunken fight on the beach one evening, but it was broken up by security very quickly. The rooms have the same toiletries as the Deluxe resorts, and the bedding seems to be of higher quality than the other moderates. The transportation was FANTASTIC- only stood on the bus twice, and we stayed for parades/fireworks. We didn't try the food court because we had access to the lounge and they served a continental breakfast and appetizers throughout the day so we had no need.
RS seemed to be a bit more crowded than FQ, but it's a larger resort and the family size also tends to be larger because the AB rooms can sleep 5. FQ is tiny, which makes it very peaceful and charming. The horse and carriages that walk through the resorts really add to the atmosphere. Transportation was wonderful! You have the option of taking either bus at the end of the night, because the 2 are such an easy walk from each other. We just hopped in line for whichever resort had the shortest line. This is also true for the boats from DTD- RS always had a very long line, but the line for FQ was nonexistent, so we took the boat to FQ and waked to RS. The downside is that the 2 often share transportation, so it takes a bit longer to get to/from the parks. The food court at RS is larger with more selections but the Beignets and FQ are amazing! RS has YeeHaw Bob (who you MUST see- great show), but you could always walk there from FQ.