Both fit the child friendly mold. We've stayed at both, now own at Resort.
Villages (SVV) is the newer of the two; it started to build as they ran out of room at the Resort (SVR). That said, SVR has just had a total refurbish and all the sections are shiny new. There are more amenities at SVR too; restaurants, pools, mini-golf, food court. SOme of the older sections at SVV are apparently getting a bit worn.
SVV being newer is all higher (5-6 story if memory serves) more densely packed buildings. All buildings have elevators (a plus), but parking is more difficult. SVR has more of a blend, but most of the lower rise sections (2-3 levels) do not have elevators. But you can usually park right at the door/stairs of your unit.
Access to the parks is easy from both, SVV is maybe 3-4 minutes further than SVR, and SVR is about 10-12 minutes from any of the Disney parking lots.
In the end, you can't go wrong with either one. I'd take whichever is offering the best deal. The kids will love both - mine have been going since around 8yo, and think of Vistana as our home in the south.
Enjoy your trip!