This is a good comparison Click Here, I know that it is from the USA so forget the pricing but it does weigh the pros and cons pretty well. If the main use by your partner is as you say then personally I would go with the Nexus 7. I like the weight, the size and it has a better processor and camera. But it is a tough choice and ideally you should see both in operation before chooding.
OnePlus 5 review