I've always switched back and forth between Android and Windows. I don't think it is accurate to say that Android is definitively better than Windows 10, or vice versa. It really depends on the individual and what they are looking for in a smartphone.
If you ask me, I think the app gap means different things to different people. Some want apps from the Google ecosystem. Some want more minor local apps that most take for granted on Android/iOS. Some want banking. Some want Snapchat, etc. Then there is the issue of some apps not being up to par with the versions on Android/iOS. I think it is things like this that bother people.
I don't use many apps at all. I just need email, calendar, a web browser, something like Viber/Whatsapp, something for reddit, weather, news, and... that's about it. All of these requirements are easily met by W10 for me. So from my point of view, I am not lacking anything on W10.
I am not just saying this either. The reason I am not using more apps on W10 is not because I am ignorant of the other apps out there on other platforms. I have a Note 5 as well. I know there are more apps on Android, and they are often more polished and kept up to date. The Microsoft ecosystem is alive and well on Android and iOS as well. Everything I do on my W10 phone, I can do just as well on my Note 5. I've just never found much utility in having a ton of apps. I am aware, however, that this is just my point of view. This might be a complete deal breaker to someone else.
So, for me, it really comes down to which OS I like better. That, unquestionably, is W10. I find it far more elegant than Android, with a good amount of customization to keep me happy. I love the live tiles, and I just generally love the whole UI. I use W10 on my computer as well, so that little bit extra integration is nice. Though, Microsoft is bringing better integration with Android with the Anniversary update, so that is nice as well.
I can't speak much for iOS. I can't stand the interface and general UI interactions in iOS. I've tried many times... I assume the situation is similar though.
On the whole, I understand what Microsoft is trying to do. I agree that focusing on W10 on phones is not a great idea this year. They really need to drive adoption of W10 and the UWP. Any success that the W10 ecosystem achieves, it will eventually trickle down to ALL devices running the OS, including phones. Microsoft is moving in the right direction.
My advice is to not force yourself to use a particular device/ecosystem out of some misguided sense of loyalty. No matter how personal these devices are to us, and they ARE, at the end of the day, they are just tools. Don't limit yourself to just one ecosystem. Try them all! Use whatever works for you at the time. If it is no longer doing what you need it to do, use something else!
That's what I think anyways.