It's whatever you're into.
To us, the BWV GV blows away Okw because of location. What's the use of having a great room, if you have to travel by car or bus to get to everything. The Vistana and Marriot resorts off of Disney property have very large rooms, but like Okw are far away from everything. Hence the parking spot in front of your room. YOU NEED IT.
It's nice to have 30 or so friends in your' room before going out for the night, knowing while you are downstairs or across the bay, your' kids are just upstairs. We usually get a GV, then about 5 or 6 rooms for friends. We meet at our place before going out. It's so nice to know we don't have to pile into 5 or 6 cars to go out for a good time. BW has the nightlife downstairs, more than one restaurant, easy access to the parks, themed pools you don't have to drive to, and so much more. It cost more points because why? it's pretty easy to figure out. To each his own, some love the Okw, others the BW, both great choices.
Try them both, until you do, you can't make a fair comparison. Some know it alls on the board try to say why there choice is so much better than the other one, but have never used the points or cash to actually stay in one. They compare them both, but haven't stayed at both. It's like someone saying a car is better than another car, but they haven't even test drove it yet. I would love to try the 3 bedroom at Vero, it looks great, but I know I don't have the knowledge to compare them to the other GVs because I haven't tried it yet. You can't go wrong with whatever resort you choose, but don't be swayed by someone's opinion who has never stayed in a GV at the BW with friends on a weekend. It's a great time.
AS for the 12 in a room, we usually do 8 to 10. Any more is pushing it, unless you want to have a camp out for the kids in the huge living room. The kids do like that once in awhile. We usually get a few more rooms for the others, so as everyone sleeps comfortable. Good luck with your choice, by the way we're staying in the BW GV in Nov, Okw GV half our trip in Feb, and the BW GV the rest of the trip. Both great choices. Enjoy!