I am an iPhone guy, but my wife needs a new android phone. She doesn't need much, so 64 GB would be plenty of memory for her. And even 32 GB is probably enough. And, if possible, I would like to keep the cost to $300 or less.
We probably won't change plans. She has a very cheap, good plan right now with MetroPCS (T-Mobile). She doesn't use much data, and her current plan is only $36 a month.