I would vote for VWL for several reasons. When my kids were younger, we usually spent more time at MK. At VWL, you can take a boat to the MK and never have to fold up the stroller. After multiple trips to WDW with one or two in strollers - folding them up on the busses became my least favorite thing to do. The same holds true for BCV and BWV as far as taking the boat to Epcot or MGM, but based on the fact that we always spent more time at MK when the kids were little - being at VWL was a plus. You are close to FW at VWL and if your kids like animals, then they would probably enjoy some time at FW. There used to be a petting zoo (don't know if it's still there), pony rides, campfire movie, etc....
There is a small kiddie pool - nothing exciting, but my youngest son, when he was little, loved the quiet pool at VWL. It has bubbles in a few places which he loved. There is Roaring Forks, which is a CS type place and Whispering Canyon which is TS, but not fancy.
VWL are quiet and relaxing. I think it's a nice retreat from the hyperstimulation that surround the children at WDW.
I should add that we've never stayed at SSR or OKW, but have stayed at BWV, BCV and VWL with young children. BCV definitely gets my vote for older children and we'll likely try to spend our next few trips there with older kids, but VWL is still my fave for young ones.