my experience was very different, sadly I would say no mobile OS is in a great state but I'm surprised people are so quick to drop the new Lumia's without seeing what the next update or two do. Windows 10 Mobile was launched with the new phones before it is ready that is true, but I haven't had that many crashes or bugs, it is more battery hungry then it should be for sure however the last couple of insider builds are much much better on other phones then previous builds battery wise and stability wise so I'm hopeful that should be fixed soon, personally I think it has huge potential.
I would say that the original launch of iOS7 was okay, however iOS 8 and 9 were terrible, at launch both had battery issues, crashing issues, I experienced reboots, on my 6s Plus my home button would randomly become too hot to touch, it would reboot every other time I opened the camera, iCloud was broken. the phone was always warm and battery life sucked even after a hard reset with a fresh set up, the home button was fixed in the first update but battery life is still problematic now and even now after a few updates I wouldn't call it stable, in my experience iOS 8 was just as bad as Windows 10 Mobile is now when it launched. I consider iOS9 a stability update thankfully where they fixed a lot of it, still has a way to go though
same with Android, KitKat was a bit of a mess but it was a huge overhaul, battery was much worse then previous version along with stability and only with Marshmallow have they fixed this for the most part, it's a huge improvement in most areas., I just hope they don't go backwards in the next version
in my opinion this constant reinventing and heaps of new features being chucked in has resulted in all platforms being unstable, Windows Phone isn't the only one, both Android and iOS are going through the same thing, my hope is that Apple, Google and Microsoft start to focus on stability now they have brought about these huge overhauls to their respective platforms which it seems like they might be.
oh and personally for me yes iOS had more apps yet I couldn't find a Reddit client anywhere as good as Readit and the official YouTube app was awful compared to Metrotube and Mytube, seriously the official YouTube app is terrible, really really bad!, I'm now hoping Google don't make one for Windows Phone it was that bad, lately they updated it and it's even worse!, I would say I'm actually happier in regards to apps on Windows Phone overall, I don't play many games or use that many apps and yes I'm likely the only person in the world to say that I know.