iPad Mini is a very foolish choice. It's only 768x1024. Should be a retina iPad instead, which is 1536x2048.
The 1536x2048 resolution of the iPad 3/4 is miles better than the 768x1024 resolution of the old iPad and the iPad Mini. Frankly, 768x1024 is insufficient for reading anything but pure text like novels. You need 1536x2048 for technical material or anything serious at all.