They are only about a minute bus ride away from each other, so I wouldn't factor that in for deciding which location! you can walk between the 2 if you wanted!
We stayed in Jambo, which is mostly regular guest rooms, I believe Kidani is mostly DVC but you can reserve them on the website as well. We need 2 queen beds, and the comparable rooms we looked at at Kidani had a queen bed and a queen sofa sleeper and I just feel if we are spending the money and going on a vacation I don't want anyone staying on a pull out, especially when we can stay next door with 2 queen beds!
Jambo has a QS restaurant, Kidani doesn't (except at the pool you can get some sandwiches and such). Honestly, they are so close to each other, and they both have nice pools and lobbies and equally amazing savannas IMO, for me it would boil down to food options and bed/room options. And price of course!! Jambo, for us, was less expensive than a Villa at Kidani. Jambo has more food options as well, and the 24 hour (I think?) Mara QS was utilized many times! Sanaa, at Kidani, is one of our favorite dinners on property, but was easily accessible by a shuttle van that goes back and forth between the 2 resorts mostly all day. Took maybe 3 minutes. If you've never stayed at AKL I would probably recommend Jambo. The lobby has more of a "wow" factor and the pool/QS/arcade are all grouped together so it is slightly more convenient.
We love AKL! Whichever side you choose I'm sure you'll love it!