Grim reading on this thread, but I get it. I just rolled my 830 back to 8.1 to get the firmware update and I'm amazed at how much better 8.1 is compared to the latest W10 build. More responsive, no crashes, and my battery life is probably twice what it was on W10. I think the app gap is getting better with UWP, but W10 has otherwise been a flop for phones.
I'll be replacing the 830 this summer, and at this point I'm strongly considering a Nexus device. I have enjoyed WP since my 900, but the bottom line is that Android has improved a lot since then and Windows has gotten worse, at least with W10 as it stands now.
Update:
Best Buy had the ZTE Maven (running Lollipop) on sale for $30 so I picked one up to give Android a test drive. (BTW, I ordered the "Aerb 5in1 Nano Micro Standard Sim Card Adapter" from Amazon for $7 to switch from the 830's nano sim to the ZTE's micro sim. It works great, with the nano sim clicking in to the adapter for the switch, rather than some that use adhesives and turn into a mess.)
Observations after couple of days use:
*The ZTE's screen and camera suck, but hey, it was $30.
*Like my 830, the ZTE uses a SD 400 with 1GB of Ram, and Android is buttery smooth. No hangups, no resuming, and I've had a lot of apps open. I'm very impressed with how well a very cheap phone can run. Even the hardware itself is decent. It's nice to hold in the hand, the screen and buttons are very responsive, and it sounds good in my $15 Skullcandy earbuds. Also, battery life is decent enough to get through a day. I have only one gripe: the Micro-usb port should never, ever, for any reason, go on the side of a phone. It's just the weirdest choice ever.
*Chrome is a revelation after using Edge on the 830. Smooth, everything renders well, no hiuccups, no bull****.
*The overall look of Lollipop is nice. Clearly Google put a lot of thought in to Material Design, and it shows.
*Google Maps and Street View kick ***. Even on this limited hardware it's smooth, fast, and detailed.
*Most apps run smoother on Android. (There are very important exceptions, which I will mention below.) A great example is Windows Central, which is quite snappy on Android and still very hit-or-miss on W10. I'm not usually one to complain about the app gap, since I think that UWP on W10 has helped a lot, but there are a few things that I like having on Android, like Zillow and my local bank's app.
*8GB is not enough storage, and juggling apps to the SD card is a pain. (But again, it's $30.)
*Notifications on Android are better than they used to be, but it still wants to notify you of everything under the sun and it takes a lot of effort to reign that in. With windows, I just let unimportant things show up on the live tile and I would get to them whenever I had time. Also, the ZTE has a notification LED in the front that blinks green, orange, or red for reasons that I can neither understand nor control. I'm pretty certain there are things I can do with this somewhere in the settings menu, but it's not obvious.
*Android doesn't handle email as well as Windows, and in particular Outlook is a far superior product on W10 mobile than Android. (Keep in mind that my work email is an Exchange active sync account.) In windows, I can control sync rates, notifications, and signatures for each account, and each account can show up on it's own live tile. No such luck in Android. Also, adding accounts to the Outlook calendar is easy in Windows, regardless of where the account is hosted. There is still no great way of putting Outlook and/or Exchange accounts to a Google calendar. The Outlook month view (which I prefer) is far more detailed in Windows than Android, and the Windows calendar live tile is far better than the Outlook calendar widget on Android. In short: email and calendar management is MUCH better in Windows.
*Contact management is also much better. This may be a function of having used a Windows phone for more than 5 years now, but my Google contacts are full of crap and not easy to clean up. And like the calendar, there doesn't seem to be a good way to import stuff from Outlook.com.
Overall I'm still on the fence, but I'm leaning towards a 950/950XL with hopes that Edge and Maps get better.