Apple iPhones are great for all their apps, even Android lovers have to acknowledge that there are more apps for the iPhone but Android is catching up and has more than you could ever use.
Androids are usually cheaper than Apple. Apple is user friendly. I bought my 75 year old mom an iPhone due to her near blindness. She can use Siri to do everything from opening apps to reading and sending text messages and calling people. She loves it and is not techie at all! That's the best thing I ever got her.
Go to the store and play with them. I personally would recommend Apple but somebody else will recommend Android so it comes down to your preference.
As far as gb go, 2 should be plenty. I have a 10 GB family share plan for 5 iPhones. Two of the users are my 20 and 24 year old daughters and we never go much over 5 GB. But we do switch to wifi at home which helps.