Some other subs can have similar topics but take different directions, but it looks like you two are the same. And both are growing and attracting users, it would be better to just combine. I remember /r/egalitarian and /r/egalitarianism on reddit did that, they closed /r/egalitarian, put a sticky up telling everybody to go to /r/egalitarianism, and I believe the active mods became mods there as well. Personally I'd prefer /v/AMA, if for nothing else it's not a complete copy of a reddit trademark. But mostly I just think it should be one sub. Staying separate just dilutes both subs and the longer it goes on, it could be more challenging to combine.