I use a Lenovo Tab3 7. So cheap but works OK.
I use it on wifi at home and free wifi spots and 'mobile hotspot' from my phone when I am out and about.
It leaves my phone free to use as a phone and I can have PoGo running at all times.
It was very cheap, and so I don't mind having it as a dedicated PoGo device.
PoGo is never off, and I can still use my phone as a phone while I play.