Nokia's only gone from the phone market...for now
ANYWAY, I completely understand your feelings and concerns regarding the future (or lack thereof) of Windows Phone. And I honestly don't urge anyone to stay on the platform or even try it anymore. However, if you're considering to switch to Android (which I totally recommend

) I would advise you to take a more serious look at the offerings on the Android spectrum and don't jump on the Nexus 6P just because it's a Nexus device.
Some hardcore Google fanboys swear by what they call "stock Android" (ie. Google's version of Android) and like to bash every single device that isn't a Nexus because it either has "bloat" or "doesn't look very Material-Design-y". But the truth is, often those "skins" that Android OEMs put on top of Google's Android actually enhance the Android experience.
Samsung's TouchWiz is the worst skin of all in terms of performance. No debate there. However you do get a plethora of additional features that you won't get on "stock" Android. The same goes for LG's UI, for HTC's Sense or for Sony's UI. They all add stuff to the Android experience that actually make it a lot better than "stock Android". So I do advise you to try out a few different phones so you get a better sense of the UIs.
And when it comes to the hardware, Nexus phones aren't exactly the cream of the crop. On the contrary, they lack a ton of stuff that is basically "standard" these days (as in, it's available on most Android flagships). And that's because when Google asks OEMs for a Nexus, they have very specific software stuff they want to showcase. The Nexus 5X and 6P, for example, are about the fingerprint scanner support on Marshmallow. That's basically what those phones are about. Kinda like the 950/XL are about Continuum except Google doesn't charge you extra to make the fingerprint scanner work.
So think well before you decide to pick up a Nexus 6P (specially because build quality apparently isn't that great with phones bending and that horrible visor on the back cracking out of nowhere). Don't let yourself be influenced by reviewers only. For example, folks at Android Central are great but they are way too biassed when it comes, for example, to Motorola (a company who has produced one of the worst Android Wear watches but that they praise to no end). Honestly, when it comes to Android, my advice is to try out the phones in store if you can.
As a fellow Nokian, though, I can tell you: when it comes to build quality, both Sony and LG haven't failed to impress me. My Z3C fell more than half a dozen times and not a single scratch. When it comes to camera quality, however, forget Sony. LG has the best camera on a smartphone currently. And there's a chance the G5 will have an even better once since LG entered into a licensing agreement with Nokia Technologies (the guys that hold Nokia's imaging patents, the ones Microsoft licenses to use on the 950/XL etc).
Nop. They really didn't. Not on photography. They do added SteadyShot for video though, and there the Z5 shines above the rest. But when you turn to the photography part of the camera, it's as crappy as the previous generations. Actually no, it's even worse because they've limited even more the so called "manual mode" on the Z5 to the point of it not really having a reason to remain there (not only that, they locked the camera2api on their phones so that you can't even use a different camera app).