I've been with Windows Phone since about 2013, and I started out with a Lumia 520 first. At its time, WP8 was amazing, Metro was amazing, the experience was consistent, smooth and it ran like a champ on what seemed like the lowest of the low. I loved every single aspect of it. The number of apps didn't matter for me, because I simply knew I couldn't get an experience like that unless I shelled out a fortune for an iPhone and even then iOS is inferior to 8/8.1 in terms of design.
Last year, I bought a Lumia 830, confident that Windows Phone would prosper and Windows 10 would be amazing. A few weeks after, the first preview was released. Hyped up, I immediately installed it. What I found was...disappointing, to say the least. It was nowhere as snappy as 8.1, the interface was inconsistent, Metro was gone, and overall it just looked like a hack. Attributing those problems to it being a preview, I didn't let my hope down. Until the Lumia 950 and 950 XL were released. At that point, I realized that those problems weren't because the software wasn't ready, it was because Microsoft didn't care. They simply didn't care. What they essentially meant by shipping Windows 10 was "this is production-ready software", when that obviously wasn't true, at least for me. My Lumia 830, which I remind was marketed as an "affordable flagship", lags and stutters more than my friends' old mid-range Android phones. Now, if Microsoft had preserved the consistent Metro language and made sure that their OS didn't lag on a mid-high end phone from the last generation, I would be happy with having less or older apps. But if my OS is worse both in experience and in app support, that's where I draw the line.
I'm switching to a Nexus 6P in 3 weeks, and I couldn't be happier. Sure, I'll miss Glance(there's Ambient Display but it seems it's nowhere as good). But even while writing this part, I had to wait for a second and think about what else I will miss. Nothing. I won't miss anything about this garbage buggy OS.
To stubborn Windows 10 users who claim that their <low-mid end device> runs smoothly: I hope that the problem is with me and you really are having a smooth experience. I know I'm not. Brand loyalty is pointless. Just let it go.
Goodbye, WP community. It's been a fun ride.