There’s pros and cons to both platforms and there’s plenty of people willing to argue each side. I wouldn’t necessarily focus on this as much as trying to find the laptop she’s most physically comfortable typing on. Also for an aspiring writer you may want to look into a screen that’s easy on the eyes over long periods.
I want to second this. Paid is only $2 a month or $20 a year. Excellent for blocking various trackers on all devices even those not on your home network.