Last year I owned at all 3...OKW, BWV and AKV (as well as HHI). We sold the AKV because we could use the OKW points at 7 months out to book AKV and we made a profit on the sale.
We first bought OKW in 2006 and bought there to get the most points for $16K. Then we added HHI because we wanted to alternate beach and WDW trips and we found it tough to book HHI in the summer months. Then we bought the AKV and it was kind of on a whim. We were trying to add to our HHI points but the deal fell through and we were about to plan a family Xmas trip where SIL also owned AKV points so we bought there too in order to use for the big family Xmas trip. It is our, me and DH's, very FAVE resort. But we like savanna view and find we can easily book that at the 7 month window.
Then, we fell in love with going to F&W in 2013 so we came home and added 80 BWV points direct to book F&W every year. I have wanted to sell the OKW points and actually would have rather sold those instead of the AKV...but MIL and FIL love to do OKW in January and they pay us to use our points so DH won't sell those. If I could own any combo (if I win powerball tonight) I would own HHI (for beach trips), BCV (for F&W), AKV (for club level) and VWL (for Xmas trips). So then I guess, to answer your question, it would be AKV...but that's if I am stinking rich. If just a regular person, I'd say BWV.
But just an aside...we bought BWV over BCV (even though direct price was the same for both) so that we could save points by booking standard view at BWV. We have since come to learn that is tough to do even as an owner and going online right at 8am on the day of the 11 month window (for studios and 2BR villas...1BR villas seem to be easier). So if that's part of your plan, you might want to bear that in mind. Very lastly, would OKW be on my list to buy...and SSR.