Our two years are up on the contract for our current phones, so we're free to get something else. We'll stay on AT&T because I'm still getting a significant corporate discount, and on top of that we have a friend in our plan that further reduces the cost.
Let me first stay that it's completely strange how people already take it for granted that they can carry a computer in their pocket connected to the knowledge of the world. When the first iPhone came out in 2007, arguably the first smart phone that demonstrated the potential and ubiquity of this connectivity, we were just taking for granted the Internet on laptops over WiFi. I do feel like the potential is enormously squandered over stupid shit like selfies and food porn, but I certainly understand how it has enabled entirely new ways of doing practically everything.
Right now, I'm using a Lumia 920, and Diana is using a cheap, $50 no-contract Lumia 520 because her 820 took a dive a few months ago and the screen broke. (It wasn't the outer glass, it was the LCD screen under it, believe it or not.) We're still enormously happy with Windows Phone as a platform. The "app gap" has mostly closed in the last two years, but it really doesn't matter because we're not really app people beyond perhaps Facebook (Diana also uses Instagram). I think the reason we find it most useful is live tiles. When we turn on the phone, we can quickly see everything that interests us, like the current temperature, what's on the calendar, and who triggered a notification for messaging or FB or whatever. I just can't see going back to the icon grid that is iOS (and to a lesser degree, Android).
Cameras are still a priority for us. The 920 has been completely fantastic in that respect. Exterior photos are generally amazing, and interior are solid if you take a little care in how you expose. The only thing that keeps it from being as good as my little (aging) Canon S95 is the lack of a physical zoom, but being on a phone it kind of makes up for that. The competition has come a long way in terms of cameras, and iPhone in particular (the big one at least) has finally come to a place that doesn't suck. Ditto for many of the high end Samsung phones.
I suspect I'll get the Lumia 830 as my next phone. It's a slight upgrade in terms of the camera, and similar hardware otherwise. It's not expensive, and I can put an SD card into it so I can just dump all music on to it instead of having to decide what to put on there. It still does wireless charging as well, which seemed like a silly feature, but now I'd hate to not have it. It doesn't appear that anything higher end is coming to AT&T, and honestly I'm not even sure that it matters. It's funny how outside of the cameras, phone specs are mostly unimportant to me.
As for Diana, that's hard to say. The 830 would be a logical upgrade for her, but she's not a fan of the larger size. They don't really make smaller phones anymore, so that puts her in a weird place. The camera on her "burner" phone is awful, so I don't think she wants to hold on to that one for the distance.