My thoughts:
First a disclaimer to Fanboys: I know Android can what iPhones can do by installing a few apps to get video chat, find my friends, iMessage type of apps and others. Please don't find it imperative to tell me this, I own android and apple devices and I DO NOT think one is more superior then the other.
Android or iOS both have their perks and frustrations, i suggest sharing both good and bad. In other words if she is getting an iPhone go the same route so the "who do you do this" questions are easier as is the iMessage, FaceTime, find my friends and family sharing. My whole family uses apple now and it is nice that if someone buys an album or app every single person also can access that app or album for free. My mother in law buys a new book every week and my wife, sister and mother all gets free books
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My wife got an iPhone years back and I also made the change for synergy and occasionally I think about switching back but the ease of FaceTime, iMessage, family sharing and a few other built in features (without installing other apps) make me stick around.