This is as bad as asking which one of your children is your favorite! I usually book either BCV or VWL, depending on whether I'll be spending more time in MK or Epcot. They both have their advantages and disadvantages. In fact they all do.
BWV - I think they have the best view opportunity of any of the villas, if you get the boardwalk view (although the view toward the Swan isn't bad either). But the long walk to the elevator if you're at the end of the building can be a pain. I also think BWV is the best located resort, being halfway between Epcot and the Studios so walking to either is easy. Sometimes it's nice not to rely on ANY transportation, other than your own two feet.
BCV - I think BCV is great because Epcot is my favorite park, and it's so close. It also has very close parking (which is handy for those grocery runs). It doesn't have the best views though (unless you get a room where you can see some of Illuminations) and the access road can be noisy. I also enjoy the public spaces in the villas for just lounging around.
VWL - I love the cozy, woodsy feeling of VWL, although I wish it had some good lake views to request as well. I really love being on Bay Lake and using the boat transportation to get around. Parking here can be inconvenient, especially if you don't get a spot in that first row. I think VWL has the best villa lobby area for just hanging out. There are so many nooks and crannies, and it always seems so quiet.
SSR - I like the convenience to DTD, but it feels removed from the rest of WDW. When you live close enough to go "whenever", if you stay too far out on the perimeter, I just feel I might as well have stayed at home and driven over for the day. SSR does have lovely landscaping and a nice pool, and being spread out, it has a relaxing air to it.
OKW - Again, this resort just feels too far removed from the rest of the World for me. I do like the room layout being different from the other villas. You feel like you're staying at a different type of resort, not just another DVC property. I also like that there are two regular beds in the studios, so no one has to use the sofabed. It is restful and peaceful. I miss the elevators though, if I get in a building without them.
If I were booking one right now, and all availability and pricing was the same, I would probably book BCV, more for the location than anything else. So that's what I voted for. But if you asked me the same question tomorrow, my answer would probably be different.
The buses are awesome and only for BCV,BC and YC so couldn't be better. The location and did I mention SAB 
make it our families absolute favorite.
