The bigger the screen size is, the better the user experience.
Wacom Cintiq 22HD: 21.5"
5. has an external memory slot
The device has a standard memory slot (such as an SD or micro SD card slot) so that you can either extend the internal storage with affordable memory modules or you can retrieve data, such as photographs, easily from a memory card.
iRULU eXpro X2s 7"
70% have it
6. battery power
Apple iPad 4 128GB WiFi + Cellular: 11560mAh
Lenovo Yoga Tab 3 Pro: 4.6mm
Acer Iconia W510-1674: 0.51g
9. has USB mass storage support
It can transfer files, music, photos via USB, no need to install additional software.