I used WP7.5 enough and I can tell you the app ecosystem isn't there. It isn't even close. In fact I have so few apps on my Windows Phone I don't bother. On Android I have a BUNCH of apps. I would say the selection is there but the quality isn't. iOS apps are still a step above. I think once you use iOS, you will realize your reliance on mobile apps. When you come back to Android, you go "Wait why don't they have an app for that?" OR "Cool same app... wtf why is it so broken and outdated looking?" On Windows Phone you go "WTF there's no app? Oh well I don't need it anyway." It's a defeatist attitude. You learn to live your life without a certain function and then now you tell everyone you don't need an app.
Seriously. Once I sat around for a banquet for 3 hours and I tried to download games on my phone. WTF was I playing? Trash like a basketball game? Kinda ridiculous.
I have an iPod Touch, and while I do indeed have a lot of apps/games downloaded to it, I very rarely use them. The only apps on my iPod that I regularly used because they weren't on my Windows Phone were Chase Mobile (which is there now) and Words With Friends, which is coming. When there is an app missing, there is often an alternative that does the job just as well, too. For example...you may not be able to get Nike Running, but I heard there's an app called DeekFit Sprint that may be even better
The exception is games, iOS certainly has a lot more of the high end games than WP, but frankly, no matter how good the quality of the game, I'm of the opinion that the vast, vast majority of smartphone games are just not fun. With a few exceptions for simple games (like the Fruit Ninjas of the world), touch controls are just not sufficient for any sort of real gaming....give me something like a Vita or DS, or nothing at all So to me at least, the comparative lack of games is meaningless.