Oh boy, you've opened a huge can of worms here. I hope this doesn't turn into a big huge fight, but it probably will.
In general people seem to prefer BWV because they like the atmosphere... being right in the middle of all of the action, yet being able to go to your room and have it be quiet and relaxing is a huge plus. You don't have to go very far to get to a pool or to the choice of several restaurants. You are walking distance from two of the major parks, both Epcot and MGM. The decor is absolutely beautiful. If it is your home resort, you can get a standard view for points that are very close to what you can get a room at OKW for. You have all of the amenities of a deluxe disney hotel such as valet parking (free for
DVC members) and full room service. The units are a bit smaller but IMO the two bedroom is about the same square footage as my apartment at home and I never feel cramped in one (though I would not put more than 2 adults and 4 kids in a 2br).
People who like OKW like it because the villas are more spacious than any other DVC property. If you have 3 kids you will need a 2 bedroom anyway (assuming you bring a spouse with you) so I do not think space would be a problem in a 2br at ANY of the villas, but some would probably disagree. Some find great importance in being able to park right outside their door, as OKW is laid out condo style, but the downside of this is that you may not be in easy walking distance of the pool or restaurant (though they do have an internal bus system). OKW is more removed from the parks and some people really enjoy getting completely away from it all (though they have a boat, I believe, to downtown disney). There are a number of pools, but no pool slides because there are no lifeguards (which may or may not be an issue for you with kids your age, plus pool hopping can help with that). There is only one restaurant on property and room service is limited to the type of stuff you can generally get at a moderate hotel (I believe it is shared with Port Orleans). Overall you can stay there for fewer points, (not TOO many fewer compared to standard view but when you start looking at preferred it really is a signficant difference).
Anyway, my preference is really for BWV but I have tried to provide a somewhat balanced view. It really depends on what things are important to you and your vacation. When I stayed at OKW I felt like I might as well not be on disney property, I was so far from the things I like doing. When it's raining, I don't care how close you can park to your villa, you will still get soaked on the way in... with valet parking at BWV you can drop your car under cover and not have to come out again. I also prefer the atmosphere at BWV, it's just much more "disney" to me. I'm sure you will get many differing opinions though!
Lisa