For me personally, I'd like to see AJ hold onto the Divas Championship for a while and establish herself as a dominant Diva. For the most part, I've enjoyed her feud with Kaitlyn as it's delivered some, quite surprisingly, very solid matches and a pretty decent storyline. I could possibly see her feuding with Layla next, while keeping Kaitlyn in the mix, or possibly Naomi as I think they could pull off some really fun matches given AJ's great use of psychology and Naomi's very impressive athleticism.
However, I'd keep the title on AJ for quite a while and bring someone up from NXT, such as Paige, and have her initiate a feud with AJ. I'd also keep the NXT Women's Championship on Paige as it would be a unique feel to have a champion vs. champion feud between a Diva that's been on the roster for a few years and one that's being brought up to the main roster. It could also be a means of giving a little extra exposure to NXT and provide sort of an example of how the Divas will be going forward, at least if the plan is to make the Divas a true women's division. If WWE is successful in securing a US TV deal for NXT this fall, then having a "rookie Diva" boldly stepping up to the main roster to challenge the women's champion on the main roster and ultimately wind up defeating her would be, in my opinion, a novel way of introducing Paige as a "new kind of Diva" to the roster in a meaningful way.