I actually, am a teenager, and I got my first "smartphone" in 2010, when the iPhone 4 came out. In 2011, I started to be intrigued by Windows Phone, so I gave the Dell Venue Pro a try. I loved it. Then I went to the Lumia 900, now the 920.
99% of my grade uses iPhones, and it is because it has the "best" apps. It has official instagram (we just got that though, but i love 6tag) and official snapchat (again, 6snap). When phones are too "big", like people think my 920 and my sisters 1020 is (she's in college, so it's fine), they tend to think you are a little different. Like for some reason in my school, if you don't have an iPhone, you aren't cool, and your phone isn't as good. I'm not sure if your daughter would be worried about people making fun of her, just because it isn't an iPhone, but I would think it would be a good idea for her to try a Windows Phone, and see if she likes it. If she likes it, she could keep it or get a different windows phone for her needs, or if she really doesn't, she can get an iPhone. I don't think you should force her to use a Windows Phone, but have her at least try it.