At the end of the day it all comes down to personal preference.
My top choice would be AKV because I found the resort magical. The lobby at Jambo made me smile every time we returned home from the parks and I just wanted to move in and live there forever. But then I've always been passionate about anything that reminds me of nature and non-western cultures and I thought that the imagineers behind this resort got the balance of woods, African art works, and wonderful landscaping just perfect.
This resort is out of the way, but I found the buses to be very efficient.
You could potentially end up with a room down the end of a very long corridor, but the same applies for BWV.
As for OKW, I've never stayed there and to be honest it's not one I personally would add as a preference. I could be wrong, but I think the studios there might have 2 beds instead of a sofa bed, which is a big bonus. It's just that I have a soft spot for theming and for this reason places like OKW, SSR, and Bay Lake Towers would be my lower priorities.
Lastly, I went to WDW like you expecting BWV to be my favourite. However in the end I discovered that I loved things about this resort and really disliked other things. The location next to Epcot and HS was excellent and it was definitely a bonus being able to enter through the back gate of Epcot. However the buses anywhere else were downright awful. It always felt like BWV was the last stop after Swan, Dolphin, and Beach Club. The boats were also awful (they took forever and got very crowded at the end of the day) but given that the walk to HS wasn't too far, we only ever felt the need to catch the boat once.
Based on the outside of the buildings and the Boardwalk itself, I loved the theming. The buildings were beautiful and it was nice to have all those shops and eateries so close - the bakery was a favourite. However, the decor inside the room was a bit dated and gaudy. It certainly didn't feel 'deluxe' to DH or I. Just painting those ugly pink walls would make a big difference IMO.
The pool with the clown slide was pretty cool for kids. It was a bit 'concrete' for my liking and I liked the lush tropical feeling of the AKL pool. But like you say, this might not matter in January anyway.
I still think you should seriously consider a split stay of 7/7. The resorts all seem to have their own charm and I think one of the perks of such a long stay is getting to experience a few. Also, you can cut down on transport time by stationing yourself in multiple areas and visiting the parks that are closest during that block of stay. The move could work well on the Universal day as you will be out all day anyway and your bags could be moved in the process.
At the end of the day though, all my recommendations are based on the personality of my family. You know your family best. Best of luck getting exactly what you want.
Yay for getting the time off work approved. May the serious planning begin