choose best option for smartphone

I will choose ZTE Axon 7  for my family, I have below reasons for this choose:

1. I think processor is important,  ZTE Axon 7 has processor 2.15GHz quad-core Qualcomm Snapdragon 820, it is good processor

2. Next factor for me is RAM, it is memory of phone for process, RAM of this phone is 4GB, 6GB (varies by region) and it is expandable up to Up to 128GB

3. Display size, resolution in this smartphone is 5.5-inch; 2,560x1,440 pixels therefore it has good resolution

4. Operating system is important too because apps  execute better, since its operating system is Android 6.0.1 Marshmallow I think, it is good option

5.Last factor is very important it is $400

Of course there are another smartphones with better factor but in this price range, this option is best for my family and me