We stayed at the Vistana in 2016, and enjoyed it. We were in a 2BR unit, and it was HUGE. King master with a big jacuzzi, and second bedroom with two beds (can't remember if they were queens or doubles). Kitchen, living room (with pull out sofa bed), and nice little washer/dryer. With a car, it was nice being able to park right outside our door, which made it easy to go out for shopping, parks, etc. It is a very spread-out resort with multiple pool areas, so depending on where you stay, you may want to drive to your desired pool (there are pools near each area, but you might want features available at a different pool). I did not use them, but there are tennis and basketball courts, if your kids are interested in non-pool activities. The mini golf course was pretty basic, but fun for us. I also think the condo-like feel of the units makes for a quieter experience than hotel-like units where people are walking up and down the halls.
I have not been to WBC, but from what I understand, their pool areas are much more extensive and elaborate. I don't know if your 12-year-old has aged-out of the pirate ship in the main pool, but it's a feature you won't find at Vistana, and WBC has a lazy river, which is great for "kids" of any age. If you plan to spend a lot of time in the water, WBC has the edge.
That said, WBC's proximity to Disney might be a drawback for you on this trip. As
@Upatnoon says, it is basically "on" Disney property (surrounded on 3 sides and right next to CBR). Will your kids feel like it's a tease to be that close to Disney, drive under the Disney welcome sign, and not go to the parks? There are Disney things to do that aren't in the parks (like resort hopping, Disney Springs, etc.), so it doesn't have to be strictly no Disney, but you're the best judge of whether or not your kids would be satisfied with a near-Disney or Disney-lite experience.
If prices were equal, I'd probably pick WBC for a trip that includes Disney and Vistana for a trip that does not.