Too many data points lacking to consider a suggestion :)<p>As most said, unless it's a surprise gift, let her decide.<p>If it is a surprise, try to get her feedback in more subtle ways (I'm pretty bad at that, but I guess asking about her girl friend's phones or something).<p>In general, it depends on your money availability, general use case, IT ecosystem at your house or where she'll be using it, etc.<p>If money is no objection, she won't be using it for programming-related stuff or obscure hobbies, can afford apps, etc. or you have a heavy Apple ecosystem, then the iPhone is probably the best bet.<p>If money is a concern, then it can be either an Android-based system or Windows Phone.<p>For the very low-end smartphones, I recommend Windows Phone, some Android smartphones are terribly underpowered and deliver an awful user experience.<p>Personally, I have an Android device because it's the one that fits my needs the most (but I do use it for programming), and my country is 90% android smartphones so I'll have every app available.